chore(display): Reimplement epic_disp_blit()

Reimplement `epic_disp_blit()` without relying on the gfx library.

epicardium/drivers/display/api.c

@@ -2,17 +2,15 @@
 #include "drivers/display/lcd.h"
 #include "drivers/display/epic_ctx.h"
 
-#include "display.h"
-#include "Fonts/fonts.h"
 #include "FreeRTOS.h"
 #include "LCD_Driver.h"
-#include "gfx.h"
 #include "gpio.h"
 #include "task.h"
 #include "tmr.h"
 #include "tmr_utils.h"
 
 #include <machine/endian.h>
+#include <string.h>
 
 static TaskHandle_t lock = NULL;
 
@@ -126,6 +124,39 @@ int epic_disp_pixel(int16_t x, int16_t y, uint16_t color)
 	return 0;
 }
 
+static uint16_t rgb565_pixel_from_buf(
+	uint8_t *img,
+	enum epic_rgb_format format,
+	int16_t width,
+	int16_t x,
+	int16_t y,
+	uint8_t *alpha
+) {
+	uint16_t tmp16;
+	uint8_t rgba[4];
+
+	switch (format) {
+	case EPIC_RGB565:
+		*alpha = 255;
+		memcpy(&tmp16, &img[y * width * 2 + x * 2], 2);
+		return tmp16;
+	case EPIC_RGBA5551:
+		memcpy(&tmp16, &img[y * width * 2 + x * 2], 2);
+		*alpha = (tmp16 & 0x01) ? 255 : 0;
+		return (tmp16 & 0xFFC0) | ((tmp16 & 0x3E) >> 1);
+	case EPIC_RGB8:
+		*alpha = 255;
+		memcpy(rgba, &img[y * width * 3 + x * 3], 3);
+		return rgb888_to_rgb565(rgba);
+	case EPIC_RGBA8:
+		memcpy(rgba, &img[y * width * 4 + x * 4], 4);
+		*alpha = rgba[3];
+		return rgb888_to_rgb565(rgba);
+	default:
+		return 0xFFFF;
+	}
+}
+
 int epic_disp_blit(
 	int16_t pos_x,
 	int16_t pos_y,
@@ -139,69 +170,27 @@ int epic_disp_blit(
 		return cl;
 	}
 
-	int16_t offset_x = (pos_x < 0) ? -pos_x : 0;
-	int16_t count_x  = width - offset_x;
-	int16_t offset_y = (pos_y < 0) ? -pos_y : 0;
-	int16_t count_y  = height - offset_y;
-
-	if (pos_x + width >= 160) {
-		count_x -= (pos_x + width) % 160;
-	}
-	if (pos_y + height >= 80) {
-		count_y -= (pos_y + height) % 80;
-	}
-
-	size_t bpp;
-	enum gfx_encoding encoding;
+	for (int16_t xsrc = 0; xsrc < width; xsrc += 1) {
+		for (int16_t ysrc = 0; ysrc < height; ysrc += 1) {
+			int16_t xscreen = pos_x + xsrc;
+			int16_t yscreen = pos_y + ysrc;
+			size_t offset   = yscreen * 160 * 2 + xscreen * 2;
+			if (xscreen < 0 || xscreen >= 160 || yscreen < 0 ||
+			    yscreen >= 80) {
+				continue;
+			}
+
+			uint8_t alpha  = 255;
+			uint16_t pixel = rgb565_pixel_from_buf(
+				img, format, width, xsrc, ysrc, &alpha
+			);
 
-	switch (format) {
-	case EPIC_RGB565:
-		bpp      = 2;
-		encoding = GFX_RGB565;
-		break;
-	case EPIC_RGBA5551:
-		bpp      = 2;
-		encoding = GFX_RGBA5551;
-		break;
-	case EPIC_RGB8:
-		bpp      = 3;
-		encoding = GFX_RGB8;
-		break;
-	case EPIC_RGBA8:
-		bpp      = 4;
-		encoding = GFX_RGBA8;
-		break;
-	default:
-		return -1;
-		break;
-	}
+			if (alpha == 0) {
+				continue;
+			}
 
-	if (offset_x == 0 && offset_y == 0 && count_x == width &&
-	    count_y == height) {
-		/* Copy full image. No cropping.*/
-		gfx_copy_region(
-			&display_screen,
-			pos_x,
-			pos_y,
-			width,
-			height,
-			encoding,
-			img
-		);
-	} else {
-		/* Copy cropped image line by line. */
-		int16_t curr_y;
-		for (curr_y = offset_y; curr_y < offset_y + count_y; curr_y++) {
-			uint8_t *line = img + (curr_y * width + offset_x) * bpp;
-			gfx_copy_region(
-				&display_screen,
-				pos_x + offset_x,
-				pos_y + curr_y,
-				count_x,
-				1,
-				encoding,
-				line
-			);
+			epicardium_ctx_fb[offset]     = (pixel & 0xFF00) >> 8;
+			epicardium_ctx_fb[offset + 1] = pixel & 0xFF;
 		}
 	}