add alpha transparency support

Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>

2 files changed, 15 insertions, 4 deletions

diff --git a/src/kmsfb-manage.c b/src/kmsfb-manage.c
index 3713e65..6b59c48 100644
--- a/src/kmsfb-manage.c
+++ b/src/kmsfb-manage.c
@@ -140,6 +140,8 @@ static int kms_data_val_set(struct kms_data *kd, const char *key, const char *va
 		kd->xpos = strtoul(value, NULL, 0);
 	else if (!strcmp(key, "ypos"))
 		kd->ypos = strtoul(value, NULL, 0);
+	else if (!strcmp(key, "alpha"))
+		kd->alpha = strtoul(value, NULL, 0);
 	else
 		return -EINVAL;
 	return 0;
@@ -780,7 +782,7 @@ static void line(const char *str)
 	printf("------------------------ %s ------------------------\n", str);
 }
 
-static int create_drm_fbs(struct kms_fb *kms_fb)
+static int create_drm_fbs(struct kms_fb *kms_fb, int alpha)
 {
 	uint32_t pixel_format;
 	uint32_t bo_handles[4] = { };
@@ -788,6 +790,11 @@ static int create_drm_fbs(struct kms_fb *kms_fb)
 	uint32_t offsets[4] = { };
 	int err, i;
 
+	if (alpha && kms_fb->bpp != 32) {
+		fprintf(stderr, "alpha needs bpp=32\n");
+		return -EINVAL;
+	}
+
 	switch (kms_fb->bpp) {
 		case 16:
 			pixel_format = DRM_FORMAT_RGB565;
@@ -796,7 +803,8 @@ static int create_drm_fbs(struct kms_fb *kms_fb)
 			pixel_format = DRM_FORMAT_BGR888;
 			break;
 		case 32:
-			pixel_format = DRM_FORMAT_XRGB8888;
+			pixel_format = alpha ? DRM_FORMAT_ARGB8888
+					     : DRM_FORMAT_XRGB8888;
 			break;
 		default:
 			fprintf(stderr, "illegal bpp: %d\n", kms_fb->bpp);
@@ -1063,7 +1071,7 @@ static int fb_create(struct drm_resource *res, int fd, const char *cmd)
 		return ret;
 
 	/* create DRM FBs */
-	ret = create_drm_fbs(fb);
+	ret = create_drm_fbs(fb, kd.alpha);
 	if (ret)
 		return ret;
 
@@ -1075,7 +1083,8 @@ static int fb_create(struct drm_resource *res, int fd, const char *cmd)
 			for (x = 0; x < fb->xres; x++) {
 				pix = fb->fb + (x * fb->bpp / 8) + y * fb->pitch;
 				*pix = ((x & 0xff) << 8) | (0xff - (y & 0xff)) |
-					(((0xff - x) & 0xff) << 16);
+					(((0xff - x) & 0xff) << 16) |
+					((((x ^ y) & 1) ? 0x00 : 0xff) << 24);
 			}
 		}
 	}
@@ -1109,6 +1118,7 @@ static void usage(const char *prgname)
 		"                                0 - (default) don't wait for vsync when panning, but honor WAITFORVSYNC\n"
 		"                                1 - never wait for vsync\n"
 		"                                2 - always wait for vsync\n"
+		"      alpha      [optional]: set to 1 to enable alpha transparency (default: 0)\n"
 		"-s                   show information about current drm state\n"
 		"                     (can be given multiple times, executed in order of options)\n"
 		"-w <windesc>         create a DRM window into a framebuffer\n"
diff --git a/src/kmsfb.h b/src/kmsfb.h
index a257246..b9d1c8a 100644
--- a/src/kmsfb.h
+++ b/src/kmsfb.h
@@ -88,6 +88,7 @@ struct kms_data {
 	int triplebuf;
 	int fill;
 	int vsync;
+	int alpha;
 };
 
 int bgi_init(struct kms_fb *fb);