From de7b6472c31671f28708ff9ee71d6546811ed809 Mon Sep 17 00:00:00 2001
From: pacien
Date: Sat, 2 Dec 2017 20:36:29 +0100
Subject: Impl. canvas blending

Signed-off-by: pacien <pacien.trangirard@pacien.net>
---
 src/blender/blender.c  | 29 +++++++++++++++++++++++++++++
 test/blender/blender.c | 29 ++++++++++++++++++++++++++---
 2 files changed, 55 insertions(+), 3 deletions(-)

diff --git a/src/blender/blender.c b/src/blender/blender.c
index 0e0835d..738811d 100644
--- a/src/blender/blender.c
+++ b/src/blender/blender.c
@@ -1,6 +1,7 @@
 #include "blender/blender.h"
 #include <assert.h>
 #include <math.h>
+#include "morpher/morpher.h"
 
 static ColorComponent blend_components(ColorComponent origin, ColorComponent target, TimeVector frame) {
   return (ColorComponent) sqrt((TIME_UNIT - frame) * pow(origin, 2) + frame * pow(target, 2));
@@ -13,3 +14,31 @@ Color blender_blend_colors(Color origin, Color target, TimeVector frame) {
                    blend_components(origin.rgba.b, target.rgba.b, frame),
                    blend_components(origin.rgba.a, target.rgba.a, frame)}};
 }
+
+void blender_blend_canvas(Canvas *canvas, Canvas *source, Canvas *target, Morphing *morphing, TimeVector frame) {
+  IntVector flat_dim;
+  CartesianVector dim, point;
+  CartesianMapping mapping;
+  Color pixel;
+
+  dim = morpher_get_dim(morphing);
+
+  assert(dim.x > 0 && dim.y > 0);
+  assert(vector_equals(dim, canvas_get_dim(canvas)));
+  assert(vector_equals(dim, canvas_get_dim(source)));
+  assert(vector_equals(dim, canvas_get_dim(target)));
+  assert(frame >= TIME_ORIGIN && frame <= TIME_UNIT);
+
+  for (flat_dim = (dim.x - 1) * (dim.y - 1); flat_dim >= 0; --flat_dim) {
+    point.x = flat_dim % dim.y;
+    point.y = flat_dim / dim.y;
+
+    mapping = morpher_get_point_mapping(morphing, point, frame);
+
+    pixel = blender_blend_colors(canvas_get_pixel(source, mapping.origin),
+                                 canvas_get_pixel(target, mapping.target),
+                                 frame);
+
+    canvas_set_pixel(canvas, point, pixel);
+  }
+}
diff --git a/test/blender/blender.c b/test/blender/blender.c
index 344ce04..9a43db0 100644
--- a/test/blender/blender.c
+++ b/test/blender/blender.c
@@ -2,14 +2,37 @@
 #include <assert.h>
 
 static void test_color_blending() {
-  Color a = {{0xFF, 0xED, 0x00, 0x00}};
-  Color b = {{0x00, 0x47, 0xAB, 0x00}};
-  Color result = blender_blend_colors(a, b, 0.125);
+  Color origin = {{0xFF, 0xED, 0x00, 0x00}};
+  Color target = {{0x00, 0x47, 0xAB, 0x00}};
+  Color result = blender_blend_colors(origin, target, 0.125);
 
   assert(color_equals(result, (Color) {{0xEE, 0xDF, 0x3C, 0x00}}));
 }
 
+static void test_canvas_blending() {
+  Morphing morphing;
+  Canvas origin, target, result;
+  CartesianVector sample_point = {13, 17};
+
+  morpher_init(&morphing, 64, 64);
+  canvas_init(&origin, 64, 64);
+  canvas_init(&target, 64, 64);
+  canvas_init(&result, 64, 64);
+
+  canvas_set_pixel(&origin, sample_point, (Color) {{0xFF, 0xED, 0x00, 0x00}});
+  canvas_set_pixel(&target, sample_point, (Color) {{0x00, 0x47, 0xAB, 0x00}});
+
+  blender_blend_canvas(&result, &origin, &target, &morphing, 0.125);
+  assert(color_equals(canvas_get_pixel(&result, sample_point), (Color) {{0xEE, 0xDF, 0x3C, 0x00}}));
+
+  canvas_free(&result);
+  canvas_free(&target);
+  canvas_free(&origin);
+  morpher_free(&morphing);
+}
+
 int main(int argc, char **argv) {
   test_color_blending();
+  test_canvas_blending();
   return 0;
 }
-- 
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