From 1136f08912786165238910f3a2e906f48cb5bda4 Mon Sep 17 00:00:00 2001
From: Tony Cook <tony@develop-help.com>
Date: Mon, 12 Nov 2012 21:09:46 +1100
Subject: [PATCH] consistently use _valid_image() internally to ensure image
 validity

and test for it.
---
 Imager.pm               | 344 +++++++++++++++++++++++++---------------
 Imager.xs               |   5 +-
 MANIFEST                |   1 +
 MANIFEST.SKIP           |   1 +
 lib/Imager/Font/Test.pm |  92 +++++++++++
 t/t01introvert.t        |  49 +++++-
 t/t020masked.t          |   9 +-
 t/t021sixteen.t         |   2 +-
 t/t022double.t          |   2 +-
 t/t023palette.t         |  41 ++++-
 t/t1000files.t          |  14 +-
 t/t21draw.t             |  21 ++-
 t/t31font.t             |  19 ++-
 t/t40scale.t            |   6 +-
 t/t55trans.t            |  10 +-
 t/t58trans2.t           |  12 +-
 t/t61filters.t          |  16 +-
 t/t62compose.t          |  17 +-
 t/t63combine.t          |   3 +-
 t/t64copyflip.t         |  31 +++-
 t/t65crop.t             |   8 +-
 t/t66paste.t            |  16 +-
 t/t67convert.t          |   8 +-
 t/t68map.t              |   9 +-
 t/t69rubthru.t          |   4 +-
 t/t90cc.t               |  15 +-
 t/t99thread.t           |  16 +-
 27 files changed, 610 insertions(+), 161 deletions(-)
 create mode 100644 lib/Imager/Font/Test.pm

diff --git a/Imager.pm b/Imager.pm
index 85f04ed2..b15b4058 100644
--- a/Imager.pm
+++ b/Imager.pm
@@ -3,7 +3,7 @@ package Imager;
 use strict;
 use vars qw($VERSION @ISA @EXPORT @EXPORT_OK %EXPORT_TAGS %formats $DEBUG %filters %DSOs $ERRSTR %OPCODES $I2P $FORMATGUESS $warn_obsolete);
 use IO::File;
-
+use Scalar::Util;
 use Imager::Color;
 use Imager::Font;
 
@@ -687,7 +687,9 @@ sub new {
 
 sub copy {
   my $self = shift;
-  unless ($self->{IMG}) { $self->{ERRSTR}='empty input image'; return undef; }
+
+  $self->_valid_image("copy")
+    or return;
 
   unless (defined wantarray) {
     my @caller = caller;
@@ -705,16 +707,19 @@ sub copy {
 sub paste {
   my $self = shift;
 
-  unless ($self->{IMG}) { 
-    $self->_set_error('empty input image');
-    return;
-  }
+  $self->_valid_image("paste")
+    or return;
+
   my %input=(left=>0, top=>0, src_minx => 0, src_miny => 0, @_);
   my $src = $input{img} || $input{src};
   unless($src) {
     $self->_set_error("no source image");
     return;
   }
+  unless ($src->_valid_image("paste")) {
+    $self->{ERRSTR} = $src->{ERRSTR} . " (for src)";
+    return;
+  }
   $input{left}=0 if $input{left} <= 0;
   $input{top}=0 if $input{top} <= 0;
 
@@ -773,7 +778,9 @@ sub paste {
 
 sub crop {
   my $self=shift;
-  unless ($self->{IMG}) { $self->{ERRSTR}='empty input image'; return undef; }
+
+  $self->_valid_image("crop")
+    or return;
   
   unless (defined wantarray) {
     my @caller = caller;
@@ -861,7 +868,8 @@ sub crop {
 sub _sametype {
   my ($self, %opts) = @_;
 
-  $self->{IMG} or return $self->_set_error("Not a valid image");
+  $self->_valid_image
+    or return;
 
   my $x = $opts{xsize} || $self->getwidth;
   my $y = $opts{ysize} || $self->getheight;
@@ -924,7 +932,9 @@ sub img_set {
 sub masked {
   my $self = shift;
 
-  $self or return undef;
+  $self->_valid_image("masked")
+    or return;
+
   my %opts = (left    => 0, 
               top     => 0, 
               right   => $self->getwidth, 
@@ -965,7 +975,7 @@ sub to_paletted {
     return;
   }
 
-  $self->_valid_image
+  $self->_valid_image("to_paletted")
     or return;
 
   my $result = Imager->new;
@@ -1006,7 +1016,7 @@ sub to_rgb8 {
     return;
   }
 
-  $self->_valid_image
+  $self->_valid_image("to_rgb8")
     or return;
 
   my $result = Imager->new;
@@ -1028,7 +1038,7 @@ sub to_rgb16 {
     return;
   }
 
-  $self->_valid_image
+  $self->_valid_image("to_rgb16")
     or return;
 
   my $result = Imager->new;
@@ -1050,7 +1060,7 @@ sub to_rgb_double {
     return;
   }
 
-  $self->_valid_image
+  $self->_valid_image("to_rgb_double")
     or return;
 
   my $result = Imager->new;
@@ -1066,10 +1076,8 @@ sub addcolors {
   my $self = shift;
   my %opts = (colors=>[], @_);
 
-  unless ($self->{IMG}) {
-    $self->_set_error("empty input image");
-    return;
-  }
+  $self->_valid_image("addcolors")
+    or return -1;
 
   my @colors = @{$opts{colors}}
     or return undef;
@@ -1089,10 +1097,8 @@ sub setcolors {
   my $self = shift;
   my %opts = (start=>0, colors=>[], @_);
 
-  unless ($self->{IMG}) {
-    $self->_set_error("empty input image");
-    return;
-  }
+  $self->_valid_image("setcolors")
+    or return;
 
   my @colors = @{$opts{colors}}
     or return undef;
@@ -1111,6 +1117,10 @@ sub setcolors {
 sub getcolors {
   my $self = shift;
   my %opts = @_;
+
+  $self->_valid_image("getcolors")
+    or return;
+
   if (!exists $opts{start} && !exists $opts{count}) {
     # get them all
     $opts{start} = 0;
@@ -1122,52 +1132,82 @@ sub getcolors {
   elsif (!exists $opts{start}) {
     $opts{start} = 0;
   }
-  
-  $self->{IMG} and 
-    return i_getcolors($self->{IMG}, $opts{start}, $opts{count});
+
+  return i_getcolors($self->{IMG}, $opts{start}, $opts{count});
 }
 
 sub colorcount {
-  i_colorcount($_[0]{IMG});
+  my ($self) = @_;
+
+  $self->_valid_image("colorcount")
+    or return -1;
+
+  return i_colorcount($self->{IMG});
 }
 
 sub maxcolors {
-  i_maxcolors($_[0]{IMG});
+  my $self = shift;
+
+  $self->_valid_image("maxcolors")
+    or return -1;
+
+  i_maxcolors($self->{IMG});
 }
 
 sub findcolor {
   my $self = shift;
   my %opts = @_;
-  $opts{color} or return undef;
 
-  $self->{IMG} and i_findcolor($self->{IMG}, $opts{color});
+  $self->_valid_image("findcolor")
+    or return;
+
+  unless ($opts{color}) {
+    $self->_set_error("findcolor: no color parameter");
+    return;
+  }
+
+  my $color = _color($opts{color})
+    or return;
+
+  return i_findcolor($self->{IMG}, $color);
 }
 
 sub bits {
   my $self = shift;
-  my $bits = $self->{IMG} && i_img_bits($self->{IMG});
+
+  $self->_valid_image("bits")
+    or return;
+
+  my $bits = i_img_bits($self->{IMG});
   if ($bits && $bits == length(pack("d", 1)) * 8) {
     $bits = 'double';
   }
-  $bits;
+  return $bits;
 }
 
 sub type {
   my $self = shift;
-  if ($self->{IMG}) {
-    return i_img_type($self->{IMG}) ? "paletted" : "direct";
-  }
+
+  $self->_valid_image("type")
+    or return;
+
+  return i_img_type($self->{IMG}) ? "paletted" : "direct";
 }
 
 sub virtual {
   my $self = shift;
-  $self->{IMG} and i_img_virtual($self->{IMG});
+
+  $self->_valid_image("virtual")
+    or return;
+
+  return i_img_virtual($self->{IMG});
 }
 
 sub is_bilevel {
   my ($self) = @_;
 
-  $self->{IMG} or return;
+  $self->_valid_image("is_bilevel")
+    or return;
 
   return i_img_is_monochrome($self->{IMG});
 }
@@ -1175,7 +1215,8 @@ sub is_bilevel {
 sub tags {
   my ($self, %opts) = @_;
 
-  $self->{IMG} or return;
+  $self->_valid_image("tags")
+    or return;
 
   if (defined $opts{name}) {
     my @result;
@@ -1211,7 +1252,9 @@ sub addtag {
   my $self = shift;
   my %opts = @_;
 
-  return -1 unless $self->{IMG};
+  $self->_valid_image("addtag")
+    or return;
+
   if ($opts{name}) {
     if (defined $opts{value}) {
       if ($opts{value} =~ /^\d+$/) {
@@ -1259,7 +1302,8 @@ sub deltag {
   my $self = shift;
   my %opts = @_;
 
-  return 0 unless $self->{IMG};
+  $self->_valid_image("deltag")
+    or return 0;
 
   if (defined $opts{'index'}) {
     return i_tags_delete($self->{IMG}, $opts{'index'});
@@ -1279,6 +1323,9 @@ sub deltag {
 sub settag {
   my ($self, %opts) = @_;
 
+  $self->_valid_image("settag")
+    or return;
+
   if ($opts{name}) {
     $self->deltag(name=>$opts{name});
     return $self->addtag(name=>$opts{name}, value=>$opts{value});
@@ -1771,11 +1818,12 @@ sub write {
 	     fax_fine=>1, @_);
   my $rc;
 
+  $self->_valid_image("write")
+    or return;
+
   $self->_set_opts(\%input, "i_", $self)
     or return undef;
 
-  unless ($self->{IMG}) { $self->{ERRSTR}='empty input image'; return undef; }
-
   my $type = $input{'type'};
   if (!$type and $input{file}) { 
     $type = $FORMATGUESS->($input{file});
@@ -1868,9 +1916,13 @@ sub write_multi {
     return;
   }
   # translate to ImgRaw
-  if (grep !UNIVERSAL::isa($_, 'Imager') || !$_->{IMG}, @images) {
-    $class->_set_error('Usage: Imager->write_multi({ options }, @images)');
-    return 0;
+  my $index = 1;
+  for my $img (@images) {
+    unless ($img->_valid_image("write_multi")) {
+      $class->_set_error($img->errstr . " (image $index)");
+      return;
+    }
+    ++$index;
   }
   $class->_set_opts($opts, "i_", @images)
     or return;
@@ -2004,7 +2056,9 @@ sub filter {
   my $self=shift;
   my %input=@_;
   my %hsh;
-  unless ($self->{IMG}) { $self->{ERRSTR}='empty input image'; return undef; }
+
+  $self->_valid_image("filter")
+    or return;
 
   if (!$input{'type'}) { $self->{ERRSTR}='type parameter missing'; return undef; }
 
@@ -2179,10 +2233,8 @@ sub scale {
     return;
   }
 
-  unless ($self->{IMG}) { 
-    $self->_set_error('empty input image'); 
-    return undef;
-  }
+  $self->_valid_image("scale")
+    or return;
 
   my ($x_scale, $y_scale, $new_width, $new_height) = 
     $self->scale_calculate(%opts)
@@ -2236,10 +2288,8 @@ sub scaleX {
     return;
   }
 
-  unless ($self->{IMG}) { 
-    $self->{ERRSTR} = 'empty input image';
-    return undef;
-  }
+  $self->_valid_image("scaleX")
+    or return;
 
   my $img = Imager->new();
 
@@ -2276,7 +2326,8 @@ sub scaleY {
     return;
   }
 
-  unless ($self->{IMG}) { $self->{ERRSTR}='empty input image'; return undef; }
+  $self->_valid_image("scaleY")
+    or return;
 
   my $img = Imager->new();
 
@@ -2307,13 +2358,15 @@ sub scaleY {
 
 sub transform {
   my $self=shift;
-  unless ($self->{IMG}) { $self->{ERRSTR}='empty input image'; return undef; }
   my %opts=@_;
   my (@op,@ropx,@ropy,$iop,$or,@parm,$expr,@xt,@yt,@pt,$numre);
 
 #  print Dumper(\%opts);
 #  xopcopdes
 
+  $self->_valid_image("transform")
+    or return;
+
   if ( $opts{'xexpr'} and $opts{'yexpr'} ) {
     if (!$I2P) {
       eval ("use Affix::Infix2Postfix;");
@@ -2405,6 +2458,15 @@ sub transform2 {
   $opts->{variables} = [ qw(x y) ];
   my ($width, $height) = @{$opts}{qw(width height)};
   if (@imgs) {
+    my $index = 1;
+    for my $img (@imgs) {
+      unless ($img->_valid_image("transform2")) {
+	Imager->_set_error($img->errstr . " (input image $index)");
+	return;
+      }
+      ++$index;
+    }
+
     $width ||= $imgs[0]->getwidth();
     $height ||= $imgs[0]->getheight();
     my $img_num = 1;
@@ -2459,13 +2521,12 @@ sub rubthrough {
   my $self=shift;
   my %opts= @_;
 
-  unless ($self->{IMG}) { 
-    $self->{ERRSTR}='empty input image'; 
-    return undef;
-  }
-  unless ($opts{src} && $opts{src}->{IMG}) {
-    $self->{ERRSTR}='empty input image for src'; 
-    return undef;
+  $self->_valid_image("rubthrough")
+    or return;
+
+  unless ($opts{src} && $opts{src}->_valid_image("rubthrough")) {
+    $self->{ERRSTR} = $opts{src}{ERRSTR} . ' (for src)';
+    return;
   }
 
   %opts = (src_minx => 0,
@@ -2502,18 +2563,16 @@ sub compose {
      @_
     );
 
-  unless ($self->{IMG}) {
-    $self->_set_error("compose: empty input image");
-    return;
-  }
+  $self->_valid_image("compose")
+    or return;
 
   unless ($opts{src}) {
     $self->_set_error("compose: src parameter missing");
     return;
   }
   
-  unless ($opts{src}{IMG}) {
-    $self->_set_error("compose: src parameter empty image");
+  unless ($opts{src}->_valid_image("compose")) {
+    $self->_set_error($opts{src}->errstr . " (for src)");
     return;
   }
   my $src = $opts{src};
@@ -2549,8 +2608,8 @@ sub compose {
   my $combine = $self->_combine($opts{combine}, 'normal');
 
   if ($opts{mask}) {
-    unless ($opts{mask}{IMG}) {
-      $self->_set_error("compose: mask parameter empty image");
+    unless ($opts{mask}->_valid_image("compose")) {
+      $self->_set_error($opts{mask}->errstr . " (for mask)");
       return;
     }
 
@@ -2584,6 +2643,10 @@ sub compose {
 sub flip {
   my $self  = shift;
   my %opts  = @_;
+
+  $self->_valid_image("flip")
+    or return;
+
   my %xlate = (h=>0, v=>1, hv=>2, vh=>2);
   my $dir;
   return () unless defined $opts{'dir'} and defined $xlate{$opts{'dir'}};
@@ -2602,6 +2665,9 @@ sub rotate {
     return;
   }
 
+  $self->_valid_image("rotate")
+    or return;
+
   if (defined $opts{right}) {
     my $degrees = $opts{right};
     if ($degrees < 0) {
@@ -2661,6 +2727,9 @@ sub matrix_transform {
   my $self = shift;
   my %opts = @_;
 
+  $self->_valid_image("matrix_transform")
+    or return;
+
   unless (defined wantarray) {
     my @caller = caller;
     warn "copy() called in void context - copy() returns the copied image at $caller[1] line $caller[2]\n";
@@ -2709,10 +2778,8 @@ sub box {
   my $self=shift;
   my $raw = $self->{IMG};
 
-  unless ($raw) {
-    $self->{ERRSTR}='empty input image';
-    return undef;
-  }
+  $self->_valid_image("box")
+    or return;
 
   my %opts = @_;
 
@@ -2790,7 +2857,10 @@ sub box {
 
 sub arc {
   my $self=shift;
-  unless ($self->{IMG}) { $self->{ERRSTR}='empty input image'; return undef; }
+
+  $self->_valid_image("arc")
+    or return;
+
   my $dflcl= [ 255, 255, 255, 255];
   my $good = 1;
   my %opts=
@@ -2892,7 +2962,9 @@ sub line {
   my %opts=(color=>$dflcl,
 	    endp => 1,
 	    @_);
-  unless ($self->{IMG}) { $self->{ERRSTR}='empty input image'; return undef; }
+
+  $self->_valid_image("line")
+    or return;
 
   unless (exists $opts{x1} and exists $opts{y1}) { $self->{ERRSTR}='missing begining coord'; return undef; }
   unless (exists $opts{x2} and exists $opts{y2}) { $self->{ERRSTR}='missing ending coord'; return undef; }
@@ -2923,7 +2995,8 @@ sub polyline {
   my $dflcl=i_color_new(0,0,0,0);
   my %opts=(color=>$dflcl,@_);
 
-  unless ($self->{IMG}) { $self->{ERRSTR}='empty input image'; return undef; }
+  $self->_valid_image("polyline")
+    or return;
 
   if (exists($opts{points})) { @points=@{$opts{points}}; }
   if (!exists($opts{points}) and exists($opts{'x'}) and exists($opts{'y'}) ) {
@@ -2962,7 +3035,8 @@ sub polygon {
   my $dflcl = i_color_new(0,0,0,0);
   my %opts = (color=>$dflcl, @_);
 
-  unless ($self->{IMG}) { $self->{ERRSTR}='empty input image'; return undef; }
+  $self->_valid_image("polygon")
+    or return;
 
   if (exists($opts{points})) {
     $opts{'x'} = [ map { $_->[0] } @{$opts{points}} ];
@@ -3009,7 +3083,8 @@ sub polybezier {
   my $dflcl=i_color_new(0,0,0,0);
   my %opts=(color=>$dflcl,@_);
 
-  unless ($self->{IMG}) { $self->{ERRSTR}='empty input image'; return undef; }
+  $self->_valid_image("polybezier")
+    or return;
 
   if (exists $opts{points}) {
     $opts{'x'}=map { $_->[0]; } @{$opts{'points'}};
@@ -3035,6 +3110,9 @@ sub flood_fill {
   my %opts = ( color=>Imager::Color->new(255, 255, 255), @_ );
   my $rc;
 
+  $self->_valid_image("flood_fill")
+    or return;
+
   unless (exists $opts{'x'} && exists $opts{'y'}) {
     $self->{ERRSTR} = "missing seed x and y parameters";
     return undef;
@@ -3252,7 +3330,8 @@ sub getscanline {
   my $self = shift;
   my %opts = ( type => '8bit', x=>0, @_);
 
-  $self->_valid_image or return;
+  $self->_valid_image("getscanline")
+    or return;
 
   defined $opts{width} or $opts{width} = $self->getwidth - $opts{x};
 
@@ -3287,7 +3366,8 @@ sub setscanline {
   my $self = shift;
   my %opts = ( x=>0, @_);
 
-  $self->_valid_image or return;
+  $self->_valid_image("setscanline")
+    or return;
 
   unless (defined $opts{'y'}) {
     $self->_set_error("missing y parameter");
@@ -3348,6 +3428,9 @@ sub getsamples {
   my $self = shift;
   my %opts = ( type => '8bit', x=>0, offset => 0, @_);
 
+  $self->_valid_image("getsamples")
+    or return;
+
   defined $opts{width} or $opts{width} = $self->getwidth - $opts{x};
 
   unless (defined $opts{'y'}) {
@@ -3418,10 +3501,8 @@ sub getsamples {
 sub setsamples {
   my $self = shift;
 
-  unless ($self->{IMG}) {
-    $self->_set_error('setsamples: empty input image');
-    return;
-  }
+  $self->_valid_image("setsamples")
+    or return;
 
   my %opts = ( x => 0, offset => 0 );
   my $data_index;
@@ -3503,6 +3584,9 @@ sub convert {
   my ($self, %opts) = @_;
   my $matrix;
 
+  $self->_valid_image("convert")
+    or return;
+
   unless (defined wantarray) {
     my @caller = caller;
     warn "convert() called in void context - convert() returns the converted image at $caller[1] line $caller[2]\n";
@@ -3621,8 +3705,8 @@ sub combine {
       $class->_set_error("src must contain image objects");
       return;
     }
-    unless ($img->{IMG}) {
-      $class->_set_error("empty input image");
+    unless ($img->_valid_image("combine")) {
+      $Imager::ERRSTR = $img->{ERRSTR} . " (src->[$index])";
       return;
     }
     push @imgs, $img->{IMG};
@@ -3652,6 +3736,9 @@ sub map {
   my ($self, %opts) = @_;
   my @chlist = qw( red green blue alpha );
 
+  $self->_valid_image("map")
+    or return;
+
   if (!exists($opts{'maps'})) {
     # make maps from channel maps
     my $chnum;
@@ -3672,15 +3759,17 @@ sub map {
 sub difference {
   my ($self, %opts) = @_;
 
+  $self->_valid_image("difference")
+    or return;
+
   defined $opts{mindist} or $opts{mindist} = 0;
 
   defined $opts{other}
     or return $self->_set_error("No 'other' parameter supplied");
-  defined $opts{other}{IMG}
-    or return $self->_set_error("No image data in 'other' image");
-
-  $self->{IMG}
-    or return $self->_set_error("No image data");
+  unless ($opts{other}->_valid_image("difference")) {
+    $self->_set_error($opts{other}->errstr . " (other image)");
+    return;
+  }
 
   my $result = Imager->new;
   $result->{IMG} = i_diff_image($self->{IMG}, $opts{other}{IMG}, 
@@ -3704,12 +3793,10 @@ sub border {
 sub getwidth {
   my $self = shift;
 
-  if (my $raw = $self->{IMG}) {
-    return i_img_get_width($raw);
-  }
-  else {
-    $self->{ERRSTR} = 'image is empty'; return undef;
-  }
+  $self->_valid_image("getwidth")
+    or return;
+
+  return i_img_get_width($self->{IMG});
 }
 
 # Get the height of an image
@@ -3717,19 +3804,20 @@ sub getwidth {
 sub getheight {
   my $self = shift;
 
-  if (my $raw = $self->{IMG}) {
-    return i_img_get_height($raw);
-  }
-  else {
-    $self->{ERRSTR} = 'image is empty'; return undef;
-  }
+  $self->_valid_image("getheight")
+    or return;
+
+  return i_img_get_height($self->{IMG});
 }
 
 # Get number of channels in an image
 
 sub getchannels {
   my $self = shift;
-  if (!defined($self->{IMG})) { $self->{ERRSTR} = 'image is empty'; return undef; }
+
+  $self->_valid_image("getchannels")
+    or return;
+
   return i_img_getchannels($self->{IMG});
 }
 
@@ -3737,7 +3825,10 @@ sub getchannels {
 
 sub getmask {
   my $self = shift;
-  if (!defined($self->{IMG})) { $self->{ERRSTR} = 'image is empty'; return undef; }
+
+  $self->_valid_image("getmask")
+    or return;
+
   return i_img_getmask($self->{IMG});
 }
 
@@ -3746,14 +3837,15 @@ sub getmask {
 sub setmask {
   my $self = shift;
   my %opts = @_;
-  if (!defined($self->{IMG})) { 
-    $self->{ERRSTR} = 'image is empty';
-    return undef;
-  }
+
+  $self->_valid_image("setmask")
+    or return;
+
   unless (defined $opts{mask}) {
     $self->_set_error("mask parameter required");
     return;
   }
+
   i_img_setmask( $self->{IMG} , $opts{mask} );
 
   1;
@@ -3764,7 +3856,10 @@ sub setmask {
 sub getcolorcount {
   my $self=shift;
   my %opts=('maxcolors'=>2**30,@_);
-  if (!defined($self->{IMG})) { $self->{ERRSTR}='image is empty'; return undef; }
+
+  $self->_valid_image("getcolorcount")
+    or return;
+
   my $rc=i_count_colors($self->{IMG},$opts{'maxcolors'});
   return ($rc==-1? undef : $rc);
 }
@@ -3773,7 +3868,10 @@ sub getcolorcount {
 # values are the number of pixels in this colour.
 sub getcolorusagehash {
   my $self = shift;
-  
+
+  $self->_valid_image("getcolorusagehash")
+    or return;
+
   my %opts = ( maxcolors => 2**30, @_ );
   my $max_colors = $opts{maxcolors};
   unless (defined $max_colors && $max_colors > 0) {
@@ -3781,11 +3879,6 @@ sub getcolorusagehash {
     return;
   }
 
-  unless (defined $self->{IMG}) {
-    $self->_set_error('empty input image'); 
-    return;
-  }
-
   my $channels= $self->getchannels;
   # We don't want to look at the alpha channel, because some gifs using it
   # doesn't define it for every colour (but only for some)
@@ -3809,6 +3902,9 @@ sub getcolorusagehash {
 sub getcolorusage {
   my $self = shift;
 
+  $self->_valid_image("getcolorusage")
+    or return;
+
   my %opts = ( maxcolors => 2**30, @_ );
   my $max_colors = $opts{maxcolors};
   unless (defined $max_colors && $max_colors > 0) {
@@ -3816,11 +3912,6 @@ sub getcolorusage {
     return;
   }
 
-  unless (defined $self->{IMG}) {
-    $self->_set_error('empty input image'); 
-    return undef;
-  }
-
   return i_get_anonymous_color_histo($self->{IMG}, $max_colors);
 }
 
@@ -3828,7 +3919,9 @@ sub getcolorusage {
 
 sub string {
   my $self = shift;
-  unless ($self->{IMG}) { $self->{ERRSTR}='empty input image'; return undef; }
+
+  $self->_valid_image("string")
+    or return;
 
   my %input=('x'=>0, 'y'=>0, @_);
   defined($input{string}) or $input{string} = $input{text};
@@ -3855,10 +3948,9 @@ sub align_string {
 
   my $img;
   if (ref $self) {
-    unless ($self->{IMG}) { 
-      $self->{ERRSTR}='empty input image'; 
-      return;
-    }
+    $self->_valid_image("align_string")
+      or return;
+
     $img = $self;
   }
   else {
diff --git a/Imager.xs b/Imager.xs
index c47884ec..27505206 100644
--- a/Imager.xs
+++ b/Imager.xs
@@ -2122,7 +2122,7 @@ i_convert(src, avmain)
 	  RETVAL
 
 
-void
+undef_int
 i_map(im, pmaps)
     Imager::ImgRaw     im
 	PREINIT:
@@ -2160,6 +2160,9 @@ i_map(im, pmaps)
           }
           i_map(im, maps, mask);
 	  myfree(maps);
+	  RETVAL = 1;
+    OUTPUT:
+	RETVAL
 
 
 
diff --git a/MANIFEST b/MANIFEST
index 31cd9713..85f0d9a4 100644
--- a/MANIFEST
+++ b/MANIFEST
@@ -185,6 +185,7 @@ lib/Imager/Font.pm
 lib/Imager/Font/BBox.pm
 lib/Imager/Font/FreeType2.pm
 lib/Imager/Font/Image.pm
+lib/Imager/Font/Test.pm		Font for testing (outputs boxes only)
 lib/Imager/Font/Truetype.pm
 lib/Imager/Font/Type1.pm	Compatibility wrapper for Imager::Font::T1
 lib/Imager/Font/Wrap.pm
diff --git a/MANIFEST.SKIP b/MANIFEST.SKIP
index ef04e5dd..b1d5a898 100644
--- a/MANIFEST.SKIP
+++ b/MANIFEST.SKIP
@@ -134,3 +134,4 @@ Makefile\.old$
 
 # sub-module build junk
 \.bak$
+MYMETA.json
\ No newline at end of file
diff --git a/lib/Imager/Font/Test.pm b/lib/Imager/Font/Test.pm
new file mode 100644
index 00000000..9617089b
--- /dev/null
+++ b/lib/Imager/Font/Test.pm
@@ -0,0 +1,92 @@
+package Imager::Font::Test;
+use strict;
+
+use base 'Imager::Font';
+
+sub new {
+  my ($class, %opts) = @_;
+
+  bless \%opts, shift;
+}
+
+sub _draw {
+  my ($self, %input) = @_;
+
+  my $text = $input{string};
+
+  my $ppn = int($input{size} * 0.5 + 0.5);
+  my $desc = int($input{size} * 0.3 + 0.5);
+  my $asc = $input{size} - $desc;
+  my $width = $ppn * length $text;
+  my $x = $input{x};
+  my $y = $input{'y'};
+  $input{align} and $y -= $asc;
+
+  $input{image}->box(color => $input{color}, xmin => $x, ymin => $y,
+		     xmax => $x + $width-1, ymax => $y + $input{size} - 1);
+
+  return 1;
+}
+
+sub _bounding_box {
+  my ($self, %input) = @_;
+
+  my $text = $input{string};
+
+  my $ppn = int($input{size} * 0.5 + 0.5);
+  my $desc = int($input{size} * 0.3 + 0.5);
+  my $asc = $input{size} - $desc;
+
+  return ( 0, -$desc, $ppn * length $text, $asc, -$desc, $asc, $ppn * length $text, 0 );
+}
+
+sub has_chars {
+  my ($self, %input) = @_;
+
+  my $text = $input{string};
+  defined $text
+    or return Imager->_set_error("has_chars: No string parameter supplied");
+
+  return (1) x length $text;
+}
+
+sub face_name {
+  "test";
+}
+
+sub glyph_names {
+  my ($self, %input) = @_;
+
+  my $text = $input{string};
+  defined $text
+    or return Imager->_set_error("glyph_names: No string parameter supplied");
+
+  return (1) x length $text;
+}
+
+1;
+
+=head1 NAME'
+
+Imager::Font::Test - font driver producing consistent output for tests.
+
+=head1 SYNOPSIS
+
+  my $font = Imager::Font::Test->new;
+
+  # use $font where you use other fonts
+
+=head1 DESCRIPTION
+
+Imager::Font::Test is intended to produce consistent output without
+being subject to the inconsistent output produced by different
+versions of font libraries.
+
+The output is simple box for the whole string.
+
+=head1 AUTHOR
+
+Tony Cook <tonyc@cpan.org>
+
+=cut
+
diff --git a/t/t01introvert.t b/t/t01introvert.t
index 612d1858..4a1e4b51 100644
--- a/t/t01introvert.t
+++ b/t/t01introvert.t
@@ -3,7 +3,7 @@
 # to make sure we get expected values
 
 use strict;
-use Test::More tests => 434;
+use Test::More tests => 466;
 
 BEGIN { use_ok(Imager => qw(:handy :all)) }
 
@@ -197,11 +197,36 @@ is($impal2->getheight, 201, "check height");
   is($impal3->type, 'paletted', "and is paletted");
 }
 
-{ # to_rgb on incomplete image
+{
   my $im = Imager->new;
   ok($im, "make empty image");
   ok(!$im->to_rgb8, "convert to rgb8");
-  is($im->errstr, "empty input image", "check message");
+  is($im->errstr, "to_rgb8: empty input image", "check message");
+  is($im->bits, undef, "can't call bits on an empty image");
+  is($im->errstr, "bits: empty input image", "check message");
+  is($im->type, undef, "can't call type on an empty image");
+  is($im->errstr, "type: empty input image", "check message");
+  is($im->virtual, undef, "can't call virtual on an empty image");
+  is($im->errstr, "virtual: empty input image", "check message");
+  is($im->is_bilevel, undef, "can't call virtual on an empty image");
+  is($im->errstr, "is_bilevel: empty input image", "check message");
+  ok(!$im->getscanline(y => 0), "can't call getscanline on an empty image");
+  is($im->errstr, "getscanline: empty input image", "check message");
+  ok(!$im->setscanline(y => 0, pixels => [ $red, $blue ]),
+     "can't call setscanline on an empty image");
+  is($im->errstr, "setscanline: empty input image", "check message");
+  ok(!$im->getsamples(y => 0), "can't call getsamples on an empty image");
+  is($im->errstr, "getsamples: empty input image", "check message");
+  is($im->getwidth, undef, "can't get width of empty image");
+  is($im->errstr, "getwidth: empty input image", "check message");
+  is($im->getheight, undef, "can't get height of empty image");
+  is($im->errstr, "getheight: empty input image", "check message");
+  is($im->getchannels, undef, "can't get channels of empty image");
+  is($im->errstr, "getchannels: empty input image", "check message");
+  is($im->getmask, undef, "can't get mask of empty image");
+  is($im->errstr, "getmask: empty input image", "check message");
+  is($im->setmask, undef, "can't set mask of empty image");
+  is($im->errstr, "setmask: empty input image", "check message");
 }
 
 { # basic checks, 8-bit direct images
@@ -1076,6 +1101,24 @@ my $psamp_outside_error = "Image position outside of image";
   }
 }
 
+{
+  my $empty = Imager->new;
+  ok(!$empty->addtag(name => "foo", value => 1),
+     "can't addtag on an empty image");
+  is($empty->errstr, "addtag: empty input image",
+    "check error message");
+  ok(!$empty->settag(name => "foo", value => 1),
+     "can't settag on an empty image");
+  is($empty->errstr, "settag: empty input image",
+    "check error message");
+  ok(!$empty->deltag(name => "foo"), "can't deltag on an empty image");
+  is($empty->errstr, "deltag: empty input image",
+     "check error message");
+  ok(!$empty->tags(name => "foo"), "can't tags on an empty image");
+  is($empty->errstr, "tags: empty input image",
+     "check error message");
+}
+
 Imager->close_log();
 
 unless ($ENV{IMAGER_KEEP_FILES}) {
diff --git a/t/t020masked.t b/t/t020masked.t
index a5200546..95d5f1a0 100644
--- a/t/t020masked.t
+++ b/t/t020masked.t
@@ -1,6 +1,6 @@
 #!perl -w
 use strict;
-use Test::More tests => 242;
+use Test::More tests => 244;
 use Imager qw(:all :handy);
 use Imager::Test qw(is_color3 is_fcolor3);
 
@@ -687,6 +687,13 @@ for my $masked (0, 1) { # psampf
 	    "check values written");
 }
 
+{
+  my $empty = Imager->new;
+  ok(!$empty->masked, "fail to make a masked image from an empty");
+  is($empty->errstr, "masked: empty input image",
+    "check error message");
+}
+
 Imager->close_log();
 
 unless ($ENV{IMAGER_KEEP_FILES}) {
diff --git a/t/t021sixteen.t b/t/t021sixteen.t
index 46d0d0dd..a1054e5c 100644
--- a/t/t021sixteen.t
+++ b/t/t021sixteen.t
@@ -210,7 +210,7 @@ cmp_ok(Imager->errstr, '=~', qr/channels must be between 1 and 4/,
   my $im = Imager->new;
   ok($im, "make empty image");
   ok(!$im->to_rgb16, "convert empty image to 16-bit");
-  is($im->errstr, "empty input image", "check message");
+  is($im->errstr, "to_rgb16: empty input image", "check message");
 }
 
 { # bounds checks
diff --git a/t/t022double.t b/t/t022double.t
index 05807715..6a2f7573 100644
--- a/t/t022double.t
+++ b/t/t022double.t
@@ -166,7 +166,7 @@ cmp_ok(Imager->errstr, '=~', qr/channels must be between 1 and 4/,
   my $im = Imager->new;
   ok($im, "make empty image");
   ok(!$im->to_rgb_double, "convert empty image to double");
-  is($im->errstr, "empty input image", "check message");
+  is($im->errstr, "to_rgb_double: empty input image", "check message");
 }
 
 my $psamp_outside_error = "Image position outside of image";
diff --git a/t/t023palette.t b/t/t023palette.t
index 0a96b8f7..db37a0bc 100644
--- a/t/t023palette.t
+++ b/t/t023palette.t
@@ -1,7 +1,7 @@
 #!perl -w
 # some of this is tested in t01introvert.t too
 use strict;
-use Test::More tests => 211;
+use Test::More tests => 226;
 BEGIN { use_ok("Imager", ':handy'); }
 
 use Imager::Test qw(image_bounds_checks test_image is_color3 isnt_image is_color4 is_fcolor3);
@@ -29,7 +29,9 @@ my $blacki = $img->addcolors(colors=>[ $black, $red, $green, $blue ]);
 print "# blacki $blacki\n";
 ok(defined $blacki && $blacki == 0, "we got the first color");
 
-ok($img->colorcount() == 4, "should have 4 colors");
+is($img->colorcount(), 4, "should have 4 colors");
+is($img->maxcolors, 256, "maxcolors always 256");
+
 my ($redi, $greeni, $bluei) = 1..3;
 
 my @all = $img->getcolors;
@@ -590,6 +592,41 @@ my $psamp_outside_error = "Image position outside of image";
 	     0, 0, 1.0, "get a pixel in float form, make sure it's blue");
 }
 
+{
+  my $empty = Imager->new;
+  ok(!$empty->to_paletted, "can't convert an empty image");
+  is($empty->errstr, "to_paletted: empty input image",
+    "check error message");
+
+  is($empty->addcolors(colors => [ $black ]), -1,
+     "can't addcolors() to an empty image");
+  is($empty->errstr, "addcolors: empty input image",
+     "check error message");
+
+  ok(!$empty->setcolors(colors => [ $black ]),
+     "can't setcolors() to an empty image");
+  is($empty->errstr, "setcolors: empty input image",
+     "check error message");
+
+  ok(!$empty->getcolors(),
+     "can't getcolors() from an empty image");
+  is($empty->errstr, "getcolors: empty input image",
+     "check error message");
+
+  is($empty->colorcount, -1, "can't colorcount() an empty image");
+  is($empty->errstr, "colorcount: empty input image",
+     "check error message");
+
+  is($empty->maxcolors, -1, "can't maxcolors() an empty image");
+  is($empty->errstr, "maxcolors: empty input image",
+     "check error message");
+
+  is($empty->findcolor(color => $blue), undef,
+     "can't findcolor an empty image");
+  is($empty->errstr, "findcolor: empty input image",
+     "check error message");
+}
+
 Imager->close_log;
 
 unless ($ENV{IMAGER_KEEP_FILES}) {
diff --git a/t/t1000files.t b/t/t1000files.t
index 22cbdf0a..4b7764b1 100644
--- a/t/t1000files.t
+++ b/t/t1000files.t
@@ -4,7 +4,7 @@
 # the file format
 
 use strict;
-use Test::More tests => 85;
+use Test::More tests => 89;
 use Imager;
 
 -d "testout" or mkdir "testout";
@@ -146,6 +146,18 @@ is(Imager->errstr, "check_file_limits: width must be a positive integer",
   }
 }
 
+{ # test empty image handling for write()/write_multi()
+  my $empty = Imager->new;
+  my $data;
+  ok(!$empty->write(data => \$data, type => "pnm"),
+     "fail to write an empty image");
+  is($empty->errstr, "write: empty input image", "check error message");
+  my $good = Imager->new(xsize => 1, ysize => 1);
+  ok(!Imager->write_multi({ data => \$data, type => "pnm" }, $good, $empty),
+     "fail to write_multi an empty image");
+  is(Imager->errstr, "write_multi: empty input image (image 2)");
+}
+
 # check file type probe
 probe_ok("49492A41", undef, "not quite tiff");
 probe_ok("4D4D0041", undef, "not quite tiff");
diff --git a/t/t21draw.t b/t/t21draw.t
index 0fb5b2e5..a1f7f2ab 100644
--- a/t/t21draw.t
+++ b/t/t21draw.t
@@ -1,6 +1,6 @@
 #!perl -w
 use strict;
-use Test::More tests => 244;
+use Test::More tests => 256;
 use Imager ':all';
 use Imager::Test qw(is_color3 is_image);
 use constant PI => 3.14159265358979;
@@ -297,6 +297,25 @@ my $white = '#FFFFFF';
   }
 }
 
+{
+  my $empty = Imager->new;
+  ok(!$empty->box(), "can't draw box to empty image");
+  is($empty->errstr, "box: empty input image", "check error message");
+  ok(!$empty->arc(), "can't draw arc to empty image");
+  is($empty->errstr, "arc: empty input image", "check error message");
+  ok(!$empty->line(x1 => 0, y1 => 0, x2 => 10, y2 => 0),
+     "can't draw line to empty image");
+  is($empty->errstr, "line: empty input image", "check error message");
+  ok(!$empty->polyline(points => [ [ 0, 0 ], [ 10, 0 ] ]),
+     "can't draw polyline to empty image");
+  is($empty->errstr, "polyline: empty input image", "check error message");
+  ok(!$empty->polygon(points => [ [ 0, 0 ], [ 10, 0 ], [ 0, 10 ] ]),
+     "can't draw polygon to empty image");
+  is($empty->errstr, "polygon: empty input image", "check error message");
+  ok(!$empty->flood_fill(x => 0, y => 0), "can't flood fill to empty image");
+  is($empty->errstr, "flood_fill: empty input image", "check error message");
+}
+
 
 malloc_state();
 
diff --git a/t/t31font.t b/t/t31font.t
index b2664859..0d1bd65b 100644
--- a/t/t31font.t
+++ b/t/t31font.t
@@ -1,7 +1,7 @@
 #!perl -w
 use strict;
 use Imager;
-use Test::More tests => 10;
+use Test::More tests => 14;
 
 unshift @INC, "t";
 
@@ -40,3 +40,20 @@ SKIP:
     or skip("Failed to load", 1);
   ok($good->isa("GoodTestFont"), "and it's the right type");
 }
+
+
+use Imager::Font::Test;
+
+# check string() and align_string() handle an empty image
+{
+  my $font = Imager::Font::Test->new;
+  my $empty = Imager->new;
+  ok(!$empty->string(text => "foo", x => 0, y => 10, size => 10, font => $font),
+     "can't draw text on an empty image");
+  is($empty->errstr, "string: empty input image",
+     "check error message");
+  ok(!$empty->align_string(text => "foo", x => 0, y => 10, size => 10, font => $font),
+     "can't draw text on an empty image");
+  is($empty->errstr, "align_string: empty input image",
+     "check error message");
+}
diff --git a/t/t40scale.t b/t/t40scale.t
index 7e2a149b..6a995548 100644
--- a/t/t40scale.t
+++ b/t/t40scale.t
@@ -103,13 +103,13 @@ ok($scaleimg->write(file=>'testout/t40scale3.ppm', type=>'pnm'),
 { # error handling - NULL image
   my $im = Imager->new;
   ok(!$im->scale(scalefactor => 0.5), "try to scale empty image");
-  is($im->errstr, "empty input image", "check error message");
+  is($im->errstr, "scale: empty input image", "check error message");
 
   # scaleX/scaleY
   ok(!$im->scaleX(scalefactor => 0.5), "try to scaleX empty image");
-  is($im->errstr, "empty input image", "check error message");
+  is($im->errstr, "scaleX: empty input image", "check error message");
   ok(!$im->scaleY(scalefactor => 0.5), "try to scaleY empty image");
-  is($im->errstr, "empty input image", "check error message");
+  is($im->errstr, "scaleY: empty input image", "check error message");
 }
 
 { # invalid qtype value
diff --git a/t/t55trans.t b/t/t55trans.t
index ba1c6a0b..5554f2a8 100644
--- a/t/t55trans.t
+++ b/t/t55trans.t
@@ -6,7 +6,7 @@ use Imager;
 eval "use Affix::Infix2Postfix; 1;"
   or plan skip_all => "No Affix::Infix2Postfix";
 
-plan tests => 6;
+plan tests => 8;
 
 #$Imager::DEBUG=1;
 
@@ -47,4 +47,10 @@ SKIP:
   }
 }
 
-
+{
+  my $empty = Imager->new;
+  ok(!$empty->transform(xexpr => "x", yexpr => "y"),
+     "fail to transform an empty image");
+  is($empty->errstr, "transform: empty input image",
+     "check error message");
+}
diff --git a/t/t58trans2.t b/t/t58trans2.t
index ab569ff2..b9ebf583 100644
--- a/t/t58trans2.t
+++ b/t/t58trans2.t
@@ -1,6 +1,6 @@
 #!perl -w
 use strict;
-use Test::More tests => 38;
+use Test::More tests => 40;
 BEGIN { use_ok('Imager'); }
 use Imager::Test qw(is_color3);
 
@@ -143,6 +143,16 @@ op_test('FF80C0', <<'EOS', 127, 0, 0, 'sat');
 0 0 getp1 sat 255 * 0.01 + 0 0 rgb
 EOS
 
+
+{
+  my $empty = Imager->new;
+  my $good = Imager->new(xsize => 1, ysize => 1);
+  ok(!Imager::transform2({ rpnexpr => "x y getp1" }, $good, $empty),
+     "can't transform an empty image");
+  is(Imager->errstr, "transform2: empty input image (input image 2)",
+     "check error message");
+}
+
 use Imager::Transform;
 
 # some simple tests
diff --git a/t/t61filters.t b/t/t61filters.t
index 84bdc447..b6f8c305 100644
--- a/t/t61filters.t
+++ b/t/t61filters.t
@@ -1,7 +1,7 @@
 #!perl -w
 use strict;
 use Imager qw(:handy);
-use Test::More tests => 116;
+use Test::More tests => 122;
 
 -d "testout" or mkdir "testout";
 
@@ -424,6 +424,20 @@ is($name, "test gradient", "check the name matches");
   is_image($diff2, $cmp2, "difference() - check image with mindist 1.1 - large samples");
 }
 
+{
+  my $empty = Imager->new;
+  ok(!$empty->filter(type => "hardinvert"), "can't filter an empty image");
+  is($empty->errstr, "filter: empty input image",
+     "check error message");
+  ok(!$empty->difference(other => $imbase), "can't difference empty image");
+  is($empty->errstr, "difference: empty input image",
+     "check error message");
+  ok(!$imbase->difference(other => $empty),
+     "can't difference against empty image");
+  is($imbase->errstr, "difference: empty input image (other image)",
+     "check error message");
+}
+
 sub test {
   my ($in, $params, $out) = @_;
 
diff --git a/t/t62compose.t b/t/t62compose.t
index d7e415bd..cbf8af30 100644
--- a/t/t62compose.t
+++ b/t/t62compose.t
@@ -1,7 +1,7 @@
 #!perl -w
 use strict;
 use Imager qw(:handy);
-use Test::More tests => 114;
+use Test::More tests => 120;
 use Imager::Test qw(is_image is_imaged);
 
 -d "testout" or mkdir "testout";
@@ -239,6 +239,21 @@ for my $type_id (sort keys %types) {
   }
 }
 
+{
+  my $empty = Imager->new;
+  my $good = Imager->new(xsize => 1, ysize => 1);
+  ok(!$empty->compose(src => $good), "can't compose to empty image");
+  is($empty->errstr, "compose: empty input image",
+     "check error message");
+  ok(!$good->compose(src => $empty), "can't compose from empty image");
+  is($good->errstr, "compose: empty input image (for src)",
+     "check error message");
+  ok(!$good->compose(src => $good, mask => $empty),
+     "can't compose with empty mask");
+  is($good->errstr, "compose: empty input image (for mask)",
+     "check error message");
+}
+
 unless ($ENV{IMAGER_KEEP_FILES}) {
   unlink @files;
 }
diff --git a/t/t63combine.t b/t/t63combine.t
index b94b97a2..6cbe88b2 100644
--- a/t/t63combine.t
+++ b/t/t63combine.t
@@ -34,7 +34,8 @@ my $test_im_dbl = test_image_double;
   # bad image error
   my $im = Imager->new;
   ok(!Imager->combine(src => [ $im ]), "empty image");
-  is(Imager->errstr, "empty input image", "check message");
+  is(Imager->errstr, "combine: empty input image (src->[0])",
+     "check message");
 }
 
 {
diff --git a/t/t64copyflip.t b/t/t64copyflip.t
index 1a0a4368..2632fd53 100644
--- a/t/t64copyflip.t
+++ b/t/t64copyflip.t
@@ -1,6 +1,6 @@
 #!perl -w
 use strict;
-use Test::More tests => 87;
+use Test::More tests => 95;
 use Imager;
 use Imager::Test qw(is_color3 is_image is_imaged test_image_double test_image isnt_image is_image_similar);
 
@@ -21,6 +21,12 @@ ok($nimg, "copy returned something");
 my $diff = Imager::i_img_diff($img->{IMG}, $nimg->{IMG});
 is_image($img, $nimg, "copy matches source");
 
+{
+  my $empty = Imager->new;
+  ok(!$empty->copy, "fail to copy an empty image");
+  is($empty->errstr, "copy: empty input image", "check error message");
+}
+
 # test if ->flip(dir=>'h')->flip(dir=>'h') doesn't alter the image
 $nimg->flip(dir=>"h")->flip(dir=>"h");
 is_image($nimg, $img, "double horiz flipped matches original");
@@ -34,6 +40,12 @@ is_image($nimg, $img, "double vertically flipped image matches original");
 $nimg->flip(dir=>"v")->flip(dir=>"h")->flip(dir=>"hv");;
 is_image($img, $nimg, "check flip with hv matches flip v then flip h");
 
+{
+  my $empty = Imager->new;
+  ok(!$empty->flip(dir => "v"), "fail to flip an empty image");
+  is($empty->errstr, "flip: empty input image", "check error message");
+}
+
 {
   my $imsrc = test_image_double;
   my $imcp = $imsrc->copy;
@@ -148,6 +160,16 @@ ok($trimg, "matrix_transform() with back returned an image");
 $trimg->write(file=>"testout/t64_trans_back.ppm")
   or print "# Cannot save: ",$trimg->errstr,"\n";
 
+{
+  my $empty = Imager->new;
+  ok(!$empty->matrix_transform(matrix => [ 1, 0, 0,
+					   0, 1, 0,
+					   0, 0, 1 ]),
+     "can't transform an empty image");
+  is($empty->errstr, "matrix_transform: empty input image",
+     "check error message");
+}
+
 sub rot_test {
   my ($src, $degrees, $count) = @_;
 
@@ -254,3 +276,10 @@ sub rot_test {
   # my $diff = $right->difference(other => $deg, mindist => 1);
   # $diff->write(file => "testout/t64rotdiff.png");
 }
+
+{
+  my $empty = Imager->new;
+  ok(!$empty->rotate(degrees => 90), "can't rotate an empty image");
+  is($empty->errstr, "rotate: empty input image",
+     "check error message");
+}
diff --git a/t/t65crop.t b/t/t65crop.t
index 3adaa151..3b19d98f 100644
--- a/t/t65crop.t
+++ b/t/t65crop.t
@@ -1,6 +1,6 @@
 #!perl -w
 use strict;
-use Test::More tests => 64;
+use Test::More tests => 66;
 use Imager;
 use Imager::Test qw(test_image);
 
@@ -182,3 +182,9 @@ SKIP:
                 "outside of image" );
     cmp_ok($src->errstr, '=~', qr/outside of the image/, "and message");
 }
+
+{
+  my $empty = Imager->new;
+  ok(!$empty->crop(left => 10), "can't crop an empty image");
+  is($empty->errstr, "crop: empty input image", "check message");
+}
diff --git a/t/t66paste.t b/t/t66paste.t
index c8f1f377..85998236 100644
--- a/t/t66paste.t
+++ b/t/t66paste.t
@@ -1,6 +1,6 @@
 #!perl -w
 use strict;
-use Test::More tests => 54;
+use Test::More tests => 60;
 
 use Imager;
 use Imager::Test qw(is_image);
@@ -25,6 +25,20 @@ ok($img->paste(img=>$nimg, top=>30, left=>30), "paste it")
 ok($img->write(type=>'pnm',file=>'testout/t66.ppm'), "save it")
   or print "# ", $img->errstr, "\n";
 
+{
+  my $empty = Imager->new;
+  ok(!$empty->paste(src => $nimg), "paste into empty image");
+  is($empty->errstr, "paste: empty input image",
+     "check error message");
+
+  ok(!$img->paste(src => $empty), "paste from empty image");
+  is($img->errstr, "paste: empty input image (for src)",
+     "check error message");
+
+  ok(!$img->paste(), "no source image");
+  is($img->errstr, "no source image");
+}
+
 # more stringent tests
 {
   my $src = Imager->new(xsize => 100, ysize => 110);
diff --git a/t/t67convert.t b/t/t67convert.t
index eccc5911..a4517cc1 100644
--- a/t/t67convert.t
+++ b/t/t67convert.t
@@ -1,7 +1,7 @@
 #!perl -w
 use strict;
 use Imager qw(:all :handy);
-use Test::More tests => 29;
+use Test::More tests => 31;
 use Imager::Test qw(test_colorf_gpix is_fcolor1 is_fcolor3);
 
 -d "testout" or mkdir "testout";
@@ -149,3 +149,9 @@ SKIP:
   is($im->errstr, "convert: invalid matrix: element 0 is not an array ref",
      "check the error message");
 }
+
+{
+  my $empty = Imager->new;
+  ok(!$empty->convert(preset => "addalpha"), "can't convert an empty image");
+  is($empty->errstr, "convert: empty input image", "check error message");
+}
diff --git a/t/t68map.t b/t/t68map.t
index b4539940..b91f43d2 100644
--- a/t/t68map.t
+++ b/t/t68map.t
@@ -1,6 +1,6 @@
 #!perl -w
 use strict;
-use Test::More tests => 6;
+use Test::More tests => 8;
 
 -d "testout" or mkdir "testout";
 
@@ -39,3 +39,10 @@ SKIP: {
   ok( $im->map(maps=>[\@map1, [], \@map2]),
       "test OO interface (maps by maps)");
 }
+
+{
+  my $empty = Imager->new;
+  ok(!$empty->map(maps => [ \@map1, \@map2, \@map3 ]),
+     "can't map an empty image");
+  is($empty->errstr, "map: empty input image", "check error message");
+}
diff --git a/t/t69rubthru.t b/t/t69rubthru.t
index ae78d1c6..a1fa3d35 100644
--- a/t/t69rubthru.t
+++ b/t/t69rubthru.t
@@ -75,9 +75,9 @@ my $oogtarg = Imager->new(xsize=>100, ysize=>100, channels=>1);
 { # check empty image errors
   my $empty = Imager->new;
   ok(!$empty->rubthrough(src => $oosrc), "check empty target");
-  is($empty->errstr, 'empty input image', "check error message");
+  is($empty->errstr, 'rubthrough: empty input image', "check error message");
   ok(!$oogtarg->rubthrough(src=>$empty), "check empty source");
-  is($oogtarg->errstr, 'empty input image for src',
+  is($oogtarg->errstr, 'rubthrough: empty input image (for src)',
      "check error message");
 }
 
diff --git a/t/t90cc.t b/t/t90cc.t
index 50a9158e..c38453e8 100644
--- a/t/t90cc.t
+++ b/t/t90cc.t
@@ -1,6 +1,6 @@
 #!perl -w
 use strict;
-use Test::More tests => 16;
+use Test::More tests => 22;
 
 use Imager;
 
@@ -69,3 +69,16 @@ Imager::init('log'=>'testout/t90cc.log');
 	    $im_g->getcolorusagehash,
 	    'color usage hash (grey)');
 }
+
+{
+  my $empty = Imager->new;
+  is($empty->getcolorcount, undef, "can't getcolorcount an empty image");
+  is($empty->errstr, "getcolorcount: empty input image",
+     "check error message");
+  is($empty->getcolorusagehash, undef, "can't getcolorusagehash an empty image");
+  is($empty->errstr, "getcolorusagehash: empty input image",
+     "check error message");
+  is($empty->getcolorusage, undef, "can't getcolorusage an empty image");
+  is($empty->errstr, "getcolorusage: empty input image",
+     "check error message");
+}
diff --git a/t/t99thread.t b/t/t99thread.t
index 0d05fe39..86e46f03 100644
--- a/t/t99thread.t
+++ b/t/t99thread.t
@@ -32,15 +32,16 @@ $INC{"Devel/Cover.pm"}
 $Test::More::VERSION =~ /^2\.00_/
   and plan skip_all => "threads are hosed in 2.00_06 and presumably all 2.00_*";
 
-plan tests => 11;
+plan tests => 13;
 
 my $thread = threads->create(sub { 1; });
 ok($thread->join, "join first thread");
 
-# these are all, or contain, XS allocated objects, if we don't
-# probably handle CLONE requests, or provide a CLONE_SKIP, we'll
-# probably see a double-free, one from the thread, and the other from
-# the main line of control.
+# these are all, or contain, XS allocated objects, if we don't handle
+# CLONE requests, or provide a CLONE_SKIP, we'll probably see a
+# double-free, one from the thread, and the other from the main line
+# of control.
+#
 # So make one of each
 
 my $im = Imager->new(xsize => 10, ysize => 10);
@@ -81,7 +82,10 @@ my $t2 = threads->create
   (
    sub {
      ok(!UNIVERSAL::isa($im->{IMG}, "Imager::ImgRaw"),
-	"the low level image object should be undef");
+	"the low level image object should become unblessed");
+     ok(!$im->_valid_image, "image no longer considered valid");
+     is($im->errstr, "images do not cross threads",
+	"check error message");
      1;
    }
   );
-- 
2.39.5