Added bitmap decoding/drawing example

common/app/screen_filetest.c

@@ -12,6 +12,9 @@ static void b_back_cb(void* button) {
         gui_screen_back();
 }
 
+
+static void image_test();
+
 static void enter(void* screen) {
 	tft_clear(HEX(0xBABECD));
 	
@@ -104,6 +107,7 @@ static void enter(void* screen) {
 	}
 	filesystem_file_close(file);
 
+	image_test();	
 }
 
 static void leave(void* screen) {
@@ -125,4 +129,47 @@ SCREEN_STRUCT* get_screen_filetest() {
 	return &screen;
 }
 
+static void image_test() {
+	//Source: http://stackoverflow.com/a/17040962/2606757
 
+	FILE_HANDLE* file = filesystem_file_open("cpu.bmp");
+	if(file==NULL) {
+		tft_print_line(10,180,BLUE,TRANSPARENT,0,"Could not open cpu.bmp");
+		return;
+	}
+
+
+	unsigned char info[54];
+	if(filesystem_file_read(file,info,54)!=F_OK) {
+		tft_print_line(10,180,BLUE,TRANSPARENT,0,"Could not read header of cpu.bmp");
+		filesystem_file_close(file);        
+		return;
+	}
+
+	// extract image height and width from header
+	int width = *(int*)&info[18];
+	int height = *(int*)&info[22];
+
+	filesystem_file_seek(file,*(int*)&info[10]);
+
+	unsigned char data [width*4];
+	tft_draw_rectangle(100-1,160-1,100-1+width,160-1+height,BLACK);
+
+	for(int i = 0; i < height; i++)
+	{
+		filesystem_file_read(file,data,width*4);
+		for(int j = 0; j < width*4; j += 4)
+		{
+			unsigned char a = data[j];
+			unsigned char r = data[j+1]; 
+			unsigned char g = data[j+2]; 
+			unsigned char b = data[j+3]; 
+			if(a!=0) {
+				tft_draw_pixel(100+j/4,160+height-1-i,RGB(r,g,b));
+			}
+		}
+	}
+
+	filesystem_file_close(file);
+
+}