Reduce stack usage of LCD_DrawWindowedImageFromFile

Author: howard0su

src/screen/320x240x16/lcd_gfx.c

@@ -496,11 +496,12 @@ void LCD_DrawWindowedImageFromFile(u16 x, u16 y, const char *file, s16 w, s16 h,
 {
     int i, j;
     FILE *fh;
+#define FILEBUF_SIZE 128
     unsigned transparent = 0;
     unsigned row_has_transparency = 0;
     (void)row_has_transparency;
 
-    u8 buf[480 * 2];
+    u8 buf[FILEBUF_SIZE * 2];
 
     if (w == 0 || h == 0)
         return;
@@ -568,13 +569,16 @@ void LCD_DrawWindowedImageFromFile(u16 x, u16 y, const char *file, s16 w, s16 h,
     LCD_DrawStart(x, y, x + w - 1, y + h - 1, DRAW_SWNE);
     /* Bitmap start is at lower-left corner */
     for (j = 0; j < h; j++) {
-        if (fread(buf, 2 * w, 1, fh) != 1)
-            break;
-        u16 *color = (u16 *)buf;
+        u16 *color = NULL;
         if(transparent) {
 #ifdef TRANSPARENT_COLOR
             //Display supports a transparent color
             for (i = 0; i < w; i++ ) {
+                if (i % FILEBUF_SIZE == 0) {
+                    fread(buf, w - i > FILEBUF_SIZE? FILEBUF_SIZE: w - i, 2, fh);
+                    color = (u16 *)buf;
+                }
+
                 u32 c;
                 if((*color & 0x8000)) {
                     //convert 1555 -> 565
@@ -589,6 +593,11 @@ void LCD_DrawWindowedImageFromFile(u16 x, u16 y, const char *file, s16 w, s16 h,
             unsigned last_pixel_transparent = row_has_transparency;
             row_has_transparency = 0;
             for (i = 0; i < w; i++ ) {
+                if (i % FILEBUF_SIZE == 0) {
+                    fread(buf, w - i > FILEBUF_SIZE? FILEBUF_SIZE: w - i, 2, fh);
+                    color = (u16 *)buf;
+                }
+
                 if((*color & 0x8000)) {
                     //convert 1555 -> 565
                     unsigned c = ((*color & 0x7fe0) << 1) | (*color & 0x1f);
@@ -609,6 +618,11 @@ void LCD_DrawWindowedImageFromFile(u16 x, u16 y, const char *file, s16 w, s16 h,
 #endif
         } else {
             for (i = 0; i < w; i++ ) {
+                if (i % FILEBUF_SIZE == 0) {
+                    fread(buf, w - i > FILEBUF_SIZE? FILEBUF_SIZE: w - i, 2, fh);
+                    color = (u16*)buf;
+                }
+
                 if (LCD_DEPTH == 1)
                     *color = (*color & 0x8410) == 0x8410 ?  0 : 0xffff;
                 LCD_DrawPixel(*color++);