separate no png support tests into a separate test file to avoid the

[imager.git] / rotate.c

diff --git a/rotate.c b/rotate.c
index 457fea0f6321bcec3fca0ecd64cc3171d57ca452..bec2b8a647bad7e6bcbecbbb15c04a43b3fd8832 100644 (file)
--- a/rotate.c
+++ b/rotate.c
@@ -17,6 +17,7 @@ Other rotations will be added as tuits become available.
 */
 
 #include "imager.h"
+#include "imageri.h"
 #include <math.h> /* for floor() */
 
 i_img *i_rotate90(i_img *src, int degrees) {
@@ -150,7 +151,6 @@ i_img *i_rotate90(i_img *src, int degrees) {
   }
 }
 
-/* hopefully this will be inlined  (it is with -O3 with gcc 2.95.4) */
 /* linear interpolation */
 static i_color interp_i_color(i_color before, i_color after, double pos,
                               int channels) {
@@ -158,8 +158,30 @@ static i_color interp_i_color(i_color before, i_color after, double pos,
   int ch;
 
   pos -= floor(pos);
-  for (ch = 0; ch < channels; ++ch)
-    out.channel[ch] = (1-pos) * before.channel[ch] + pos * after.channel[ch];
+  if (channels == 1 || channels == 3) {
+    for (ch = 0; ch < channels; ++ch)
+      out.channel[ch] = (1-pos) * before.channel[ch] + pos * after.channel[ch];
+  }
+  else {
+    int total_cover = (1-pos) * before.channel[channels-1]
+      + pos * after.channel[channels-1];
+
+    total_cover = I_LIMIT_8(total_cover);
+    if (total_cover) {
+      double before_alpha = before.channel[channels-1] / 255.0;
+      double after_alpha = after.channel[channels-1] / 255.0;
+      double total_alpha = before_alpha * (1-pos) + after_alpha * pos;
+
+      for (ch = 0; ch < channels-1; ++ch) {
+       int out_level = ((1-pos) * before.channel[ch] * before_alpha + 
+                        pos * after.channel[ch] * after_alpha + 0.5) / total_alpha;
+
+       out.channel[ch] = I_LIMIT_8(out_level);
+      }
+    }
+
+    out.channel[channels-1] = total_cover;
+  }
 
   return out;
 }
@@ -172,14 +194,36 @@ static i_fcolor interp_i_fcolor(i_fcolor before, i_fcolor after, double pos,
   int ch;
 
   pos -= floor(pos);
-  for (ch = 0; ch < channels; ++ch)
-    out.channel[ch] = (1-pos) * before.channel[ch] + pos * after.channel[ch];
+  if (channels == 1 || channels == 3) {
+    for (ch = 0; ch < channels; ++ch)
+      out.channel[ch] = (1-pos) * before.channel[ch] + pos * after.channel[ch];
+  }
+  else {
+    double total_cover = (1-pos) * before.channel[channels-1]
+      + pos * after.channel[channels-1];
+
+    total_cover = I_LIMIT_DOUBLE(total_cover);
+    if (total_cover) {
+      double before_alpha = before.channel[channels-1];
+      double after_alpha = after.channel[channels-1];
+      double total_alpha = before_alpha * (1-pos) + after_alpha * pos;
+
+      for (ch = 0; ch < channels-1; ++ch) {
+       double out_level = ((1-pos) * before.channel[ch] * before_alpha + 
+                        pos * after.channel[ch] * after_alpha) / total_alpha;
+
+       out.channel[ch] = I_LIMIT_DOUBLE(out_level);
+      }
+    }
+
+    out.channel[channels-1] = total_cover;
+  }
 
   return out;
 }
 
-i_img *i_matrix_transform_bg(i_img *src, int xsize, int ysize, double *matrix,
-                            i_color *backp, i_fcolor *fbackp) {
+i_img *i_matrix_transform_bg(i_img *src, int xsize, int ysize, const double *matrix,
+                            const i_color *backp, const i_fcolor *fbackp) {
   i_img *result = i_sametype(src, xsize, ysize);
   int x, y;
   int ch;
@@ -211,14 +255,17 @@ i_img *i_matrix_transform_bg(i_img *src, int xsize, int ysize, double *matrix,
           /* dividing by sz gives us the ability to do perspective 
              transforms */
           sz = x * matrix[6] + y * matrix[7] + matrix[8];
-          if (abs(sz) > 0.0000001) {
+          if (fabs(sz) > 0.0000001) {
             sx = (x * matrix[0] + y * matrix[1] + matrix[2]) / sz;
             sy = (x * matrix[3] + y * matrix[4] + matrix[5]) / sz;
           }
+         else {
+           sx = sy = 0;
+         }
 
           /* anything outside these ranges is either a broken co-ordinate
              or outside the source */
-          if (abs(sz) > 0.0000001 
+          if (fabs(sz) > 0.0000001 
               && sx >= -1 && sx < src->xsize
               && sy >= -1 && sy < src->ysize) {
 
@@ -286,14 +333,17 @@ i_img *i_matrix_transform_bg(i_img *src, int xsize, int ysize, double *matrix,
           /* dividing by sz gives us the ability to do perspective 
              transforms */
           sz = x * matrix[6] + y * matrix[7] + matrix[8];
-          if (abs(sz) > 0.0000001) {
+          if (fabs(sz) > 0.0000001) {
             sx = (x * matrix[0] + y * matrix[1] + matrix[2]) / sz;
             sy = (x * matrix[3] + y * matrix[4] + matrix[5]) / sz;
           }
+          else {
+            sx = sy = 0;
+          }
 
           /* anything outside these ranges is either a broken co-ordinate
              or outside the source */
-          if (abs(sz) > 0.0000001 
+          if (fabs(sz) > 0.0000001 
               && sx >= -1 && sx < src->xsize
               && sy >= -1 && sy < src->ysize) {
 
@@ -390,6 +440,9 @@ i_img *i_matrix_transform_bg(i_img *src, int xsize, int ysize, double *matrix,
           sx = (x * matrix[0] + y * matrix[1] + matrix[2]) / sz;
           sy = (x * matrix[3] + y * matrix[4] + matrix[5]) / sz;
         }
+        else {
+          sx = sy = 0;
+        }
         
         /* anything outside these ranges is either a broken co-ordinate
            or outside the source */
@@ -415,12 +468,12 @@ i_img *i_matrix_transform_bg(i_img *src, int xsize, int ysize, double *matrix,
   return result;
 }
 
-i_img *i_matrix_transform(i_img *src, int xsize, int ysize, double *matrix) {
+i_img *i_matrix_transform(i_img *src, int xsize, int ysize, const double *matrix) {
   return i_matrix_transform_bg(src, xsize, ysize, matrix, NULL, NULL);
 }
 
 static void
-i_matrix_mult(double *dest, double *left, double *right) {
+i_matrix_mult(double *dest, const double *left, const double *right) {
   int i, j, k;
   double accum;
   
@@ -436,7 +489,7 @@ i_matrix_mult(double *dest, double *left, double *right) {
 }
 
 i_img *i_rotate_exact_bg(i_img *src, double amount, 
-                        i_color *backp, i_fcolor *fbackp) {
+                        const i_color *backp, const i_fcolor *fbackp) {
   double xlate1[9] = { 0 };
   double rotate[9];
   double xlate2[9] = { 0 };
@@ -469,9 +522,9 @@ i_img *i_rotate_exact_bg(i_img *src, double amount,
   newysize = y1 > y2 ? y1 : y2;
   /* translate the centre back to the center of the image */
   xlate2[0] = 1;
-  xlate2[2] = -newxsize/2;
+  xlate2[2] = -newxsize/2.0;
   xlate2[4] = 1;
-  xlate2[5] = -newysize/2;
+  xlate2[5] = -newysize/2.0;
   xlate2[8] = 1;
   i_matrix_mult(temp, xlate1, rotate);
   i_matrix_mult(matrix, temp, xlate2);