display: sdl: Add support for AL_88 color format

The SDL display driver can now handle and display AL_88 content.

Signed-off-by: Martin Stumpf <[email protected]>

Author: Finomnis

doc/releases/release-notes-4.3.rst

@@ -89,6 +89,10 @@ New APIs and options
 
   * Added new pixel format :c:enum:`PIXEL_FORMAT_AL_88`
 
+  * SDL
+
+    * :kconfig:option:`CONFIG_SDL_DISPLAY_DEFAULT_PIXEL_FORMAT_AL_88`
+
 * Logging:
 
   * Added rate-limited logging macros to prevent log flooding when messages are generated frequently.

drivers/display/Kconfig.sdl

@@ -40,6 +40,9 @@ choice SDL_DISPLAY_DEFAULT_PIXEL_FORMAT
 	config SDL_DISPLAY_DEFAULT_PIXEL_FORMAT_L_8
 		bool "Grayscale 8bit"
 
+	config SDL_DISPLAY_DEFAULT_PIXEL_FORMAT_AL_88
+		bool "Grayscale 8bit with Alpha"
+
 endchoice
 
 config SDL_DISPLAY_ZOOM_PCT

drivers/display/display_sdl.c

@@ -160,6 +160,8 @@ static int sdl_display_init(const struct device *dev)
 		PIXEL_FORMAT_BGR_565
 #elif defined(CONFIG_SDL_DISPLAY_DEFAULT_PIXEL_FORMAT_L_8)
 		PIXEL_FORMAT_L_8
+#elif defined(CONFIG_SDL_DISPLAY_DEFAULT_PIXEL_FORMAT_AL_88)
+		PIXEL_FORMAT_AL_88
 #else  /* SDL_DISPLAY_DEFAULT_PIXEL_FORMAT */
 		PIXEL_FORMAT_ARGB_8888
 #endif /* SDL_DISPLAY_DEFAULT_PIXEL_FORMAT */
@@ -210,6 +212,31 @@ static void sdl_display_write_rgb888(uint8_t *disp_buf,
 	}
 }
 
+static void sdl_display_write_al88(uint8_t *disp_buf,
+		const struct display_buffer_descriptor *desc, const void *buf)
+{
+	uint32_t w_idx;
+	uint32_t h_idx;
+	uint32_t pixel;
+	const uint8_t *byte_ptr;
+
+	__ASSERT((desc->pitch * 2U * desc->height) <= desc->buf_size,
+			"Input buffer too small");
+
+	for (h_idx = 0U; h_idx < desc->height; ++h_idx) {
+		for (w_idx = 0U; w_idx < desc->width; ++w_idx) {
+			byte_ptr = (const uint8_t *)buf +
+				((h_idx * desc->pitch) + w_idx) * 2U;
+			pixel = *(byte_ptr + 1) << 24;
+			pixel |= *(byte_ptr) << 16;
+			pixel |= *(byte_ptr) << 8;
+			pixel |= *(byte_ptr);
+			*((uint32_t *)disp_buf) = pixel;
+			disp_buf += 4;
+		}
+	}
+}
+
 static void sdl_display_write_rgb565(uint8_t *disp_buf,
 		const struct display_buffer_descriptor *desc, const void *buf)
 {
@@ -392,6 +419,8 @@ static int sdl_display_write(const struct device *dev, const uint16_t x,
 		sdl_display_write_bgr565(disp_data->buf, desc, buf);
 	} else if (disp_data->current_pixel_format == PIXEL_FORMAT_L_8) {
 		sdl_display_write_l8(disp_data->buf, desc, buf);
+	} else if (disp_data->current_pixel_format == PIXEL_FORMAT_AL_88) {
+		sdl_display_write_al88(disp_data->buf, desc, buf);
 	}
 
 	if (k_current_get() == &disp_data->sdl_thread) {
@@ -543,6 +572,29 @@ static void sdl_display_read_l8(const uint8_t *read_buf,
 	}
 }
 
+static void sdl_display_read_al88(const uint8_t *read_buf,
+				const struct display_buffer_descriptor *desc, void *buf)
+{
+	uint32_t w_idx;
+	uint32_t h_idx;
+	uint8_t *buf8;
+	const uint32_t *pix_ptr;
+
+	__ASSERT((desc->pitch * 2U * desc->height) <= desc->buf_size, "Read buffer is too small");
+
+	for (h_idx = 0U; h_idx < desc->height; ++h_idx) {
+		buf8 = ((uint8_t *)buf) + desc->pitch * 2U * h_idx;
+
+		for (w_idx = 0U; w_idx < desc->width; ++w_idx) {
+			pix_ptr = (const uint32_t *)read_buf + ((h_idx * desc->pitch) + w_idx);
+			*buf8 = (*pix_ptr & 0xFF);
+			buf8 += 1;
+			*buf8 = (*pix_ptr & 0xFF000000) >> 24;
+			buf8 += 1;
+		}
+	}
+}
+
 static int sdl_display_read(const struct device *dev, const uint16_t x, const uint16_t y,
 			    const struct display_buffer_descriptor *desc, void *buf)
 {
@@ -580,6 +632,8 @@ static int sdl_display_read(const struct device *dev, const uint16_t x, const ui
 		sdl_display_read_bgr565(disp_data->read_buf, desc, buf);
 	} else if (disp_data->current_pixel_format == PIXEL_FORMAT_L_8) {
 		sdl_display_read_l8(disp_data->read_buf, desc, buf);
+	} else if (disp_data->current_pixel_format == PIXEL_FORMAT_AL_88) {
+		sdl_display_read_al88(disp_data->read_buf, desc, buf);
 	}
 	k_mutex_unlock(&disp_data->task_mutex);
 
@@ -615,6 +669,9 @@ static int sdl_display_clear(const struct device *dev)
 	case PIXEL_FORMAT_BGR_565:
 		size = config->width * config->height * 2U;
 		break;
+	case PIXEL_FORMAT_AL_88:
+		size = config->width * config->height * 2U;
+		break;
 	default:
 		__ASSERT_MSG_INFO("Pixel format not supported");
 		return -EINVAL;
@@ -688,7 +745,8 @@ static void sdl_display_get_capabilities(
 		PIXEL_FORMAT_MONO10 |
 		PIXEL_FORMAT_RGB_565 |
 		PIXEL_FORMAT_BGR_565 |
-		PIXEL_FORMAT_L_8;
+		PIXEL_FORMAT_L_8 |
+		PIXEL_FORMAT_AL_88;
 	capabilities->current_pixel_format = disp_data->current_pixel_format;
 	capabilities->screen_info =
 		(IS_ENABLED(CONFIG_SDL_DISPLAY_MONO_VTILED) ? SCREEN_INFO_MONO_VTILED : 0) |
@@ -708,6 +766,7 @@ static int sdl_display_set_pixel_format(const struct device *dev,
 	case PIXEL_FORMAT_RGB_565:
 	case PIXEL_FORMAT_BGR_565:
 	case PIXEL_FORMAT_L_8:
+	case PIXEL_FORMAT_AL_88:
 		disp_data->current_pixel_format = pixel_format;
 		return 0;
 	default: