From 4101110f20fdabb6d920025c2a7bdb97d4673afc Mon Sep 17 00:00:00 2001
From: Romain Goyet <romain.goyet@numworks.com>
Date: Tue, 27 Sep 2016 12:32:15 +0200
Subject: [PATCH] [escher] The image inliner produces proper RGB565
 little-endian images

Change-Id: I96f6df798911657b9582cc264ee1d2c3ebada690
---
 escher/image/inliner.c | 23 ++++++++++++++++-------
 1 file changed, 16 insertions(+), 7 deletions(-)

diff --git a/escher/image/inliner.c b/escher/image/inliner.c
index 42c81549c..8a9b45073 100644
--- a/escher/image/inliner.c
+++ b/escher/image/inliner.c
@@ -18,7 +18,7 @@
 #define MAX_FILENAME_LENGTH 255
 
 void generateHeaderFromImage(FILE * file, const char * guardian, const char * variable);
-void generateImplementationFromImage(FILE * file, const char * header, const char * variable, uint32_t width, uint32_t height, uint32_t ** pixelsRowPointers);
+void generateImplementationFromImage(FILE * file, const char * header, const char * variable, uint32_t width, uint32_t height, png_bytep * pixelsRowPointers);
 void fileNameToSnakeCaseName(const char * fileName, char * snakeCaseName, size_t maxLength);
 void snakeCaseNameToUpperSnakeName(const char * snakeCaseName, char * upperSnakeCaseName, size_t maxLength);
 void camelCaseNameFromSnakeCaseNames(const char * snakeCaseName, const char * upperSnakeCaseName, char * camelCaseName, size_t maxLength);
@@ -93,7 +93,7 @@ int main(int argc, char * argv[]) {
   fclose(header);
 
   FILE * implementation = fopen(implementationPath, "w");
-  generateImplementationFromImage(implementation, lowerSnakeCaseName, camelCaseName, width, height, (uint32_t **)rowPointers);
+  generateImplementationFromImage(implementation, lowerSnakeCaseName, camelCaseName, width, height, rowPointers);
   fclose(implementation);
 
   fclose(inputFile);
@@ -142,19 +142,28 @@ void generateHeaderFromImage(FILE * file, const char * guardian, const char * va
   fprintf(file, "#endif\n");
 }
 
-void generateImplementationFromImage(FILE * file, const char * header, const char * variable, uint32_t width, uint32_t height, uint32_t ** pixelsRowPointers) {
+void generateImplementationFromImage(FILE * file, const char * header, const char * variable, uint32_t width, uint32_t height, png_bytep * pixelsRowPointers) {
   fprintf(file, "// This file is auto-generated by Inliner. Do not edit manually.\n");
   fprintf(file, "#include \"%s.h\"\n\n", header);
   fprintf(file, "const unsigned char data[] = {");
   for (int j=0; j<height; j++) {
+    png_bytep pixelRow = pixelsRowPointers[j];
     for (int i=0; i<width; i++) {
       if ((i+j*width) % 6 == 0) {
         fprintf(file, "\n  ");
       }
-      uint32_t rgba = pixelsRowPointers[j][i];
-      uint16_t rgb565 = (((rgba&0xF8000000)>>16)|((rgba&0x00FC0000)>>14)|((rgba&0x0000F800)>>11));
-      //if (rgba & 0xFF == 0) { rgb565 = 0xFFFF; }
-      fprintf(file, "0x%02X, 0x%02X", rgb565 >> 8, rgb565 & 0xFF);
+      png_bytep pixel = &(pixelRow[i*4]);
+      double red = pixel[0]/255.0;
+      double green = pixel[1]/255.0;
+      double blue = pixel[2]/255.0;
+      double alpha = pixel[3]/255.0;
+      // Assume a white background (1.0, 1.0, 1.0) in the blending
+      double blendedRed = red*alpha + 1.0*(1.0-alpha);
+      double blendedGreen = green*alpha + 1.0*(1.0-alpha);
+      double blendedBlue = blue*alpha + 1.0*(1.0-alpha);
+      // Merge in a RGB565
+      uint16_t rgb565 = ((uint16_t)(blendedRed*0x1F) << 11) | ((uint16_t)(blendedGreen*0x3F) << 5) | ((uint16_t)(blendedBlue*0x1F));
+      fprintf(file, "0x%02X, 0x%02X", rgb565 & 0xFF, rgb565 >> 8);
       if (i!=width-1 || j!= height-1) {
         fprintf(file, ", ");
       }