add alpha blending... - lel - Farbfeld image viewer
(HTM) git clone git://git.codemadness.org/lel
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---
(DIR) commit ab9cbe037f3c83444be66af5531f2f4bc61cb0c4
(DIR) parent 77d29cab890dd1623b96d445cf0b898ff8c09df8
(HTM) Author: Hiltjo Posthuma <hiltjo@codemadness.org>
Date: Sat, 2 Aug 2014 23:53:54 +0000
add alpha blending...
... and add configurable background colour.
Diffstat:
M lel.c | 17 ++++++++++++-----
1 file changed, 12 insertions(+), 5 deletions(-)
---
(DIR) diff --git a/lel.c b/lel.c
@@ -44,11 +44,14 @@ static struct img *cimg;
static size_t nimgs;
static int viewmode = ASPECT;
static char *wintitle = APP_NAME;
+static char *bgcolor = "#000000";
static XImage *ximg = NULL;
static Drawable xpix = 0;
static Display *dpy = NULL;
+static Colormap cmap;
static Window win;
static GC gc;
+static XColor bg;
static int screen, xfd;
static int running = 1;
static int winwidth = 0, winheight = 0;
@@ -231,6 +234,7 @@ scale(unsigned int width, unsigned int height, unsigned int bytesperline,
{
unsigned char *ibuf;
unsigned int jdy, dx, bufx, x, y;
+ float a = 0.0f;
jdy = bytesperline / 4 - width;
dx = (cimg->width << 10) / width;
@@ -239,9 +243,10 @@ scale(unsigned int width, unsigned int height, unsigned int bytesperline,
ibuf = &cimg->buf[y * cimg->height / height * cimg->width * 4];
for(x = 0; x < width; x++) {
- *newbuf++ = (ibuf[(bufx >> 10)*4+2]);
- *newbuf++ = (ibuf[(bufx >> 10)*4+1]);
- *newbuf++ = (ibuf[(bufx >> 10)*4+0]);
+ a = (ibuf[(bufx >> 10)*4+3]) / 255.0f;
+ *newbuf++ = (ibuf[(bufx >> 10)*4+2] * a) + (bg.blue * (1 - a));
+ *newbuf++ = (ibuf[(bufx >> 10)*4+1] * a) + (bg.green * (1 - a));
+ *newbuf++ = (ibuf[(bufx >> 10)*4+0] * a) + (bg.red * (1 - a));
newbuf++;
bufx += dx;
}
@@ -308,7 +313,7 @@ draw(void)
xoffset -= cimg->view.panxoffset;
yoffset -= cimg->view.panyoffset;
}
- XSetForeground(dpy, gc, BlackPixel(dpy, 0));
+ XSetForeground(dpy, gc, bg.pixel);
XFillRectangle(dpy, xpix, gc, 0, 0, winwidth, winheight);
XPutImage(dpy, xpix, gc, ximg, 0, 0, xoffset, yoffset, ximg->width, ximg->height);
XCopyArea(dpy, xpix, win, gc, 0, 0, winwidth, winheight, 0, 0);
@@ -513,7 +518,9 @@ setup(void)
DefaultDepth(dpy, screen), InputOutput,
CopyFromParent, 0, NULL);
gc = XCreateGC(dpy, win, 0, NULL);
-
+ cmap = DefaultColormap(dpy, screen);
+ if(!XAllocNamedColor(dpy, cmap, bgcolor, &bg, &bg))
+ die("cannot allocate color\n");
XStoreName(dpy, win, wintitle);
XSelectInput(dpy, win, StructureNotifyMask | ExposureMask | KeyPressMask |
ButtonPressMask);