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Don't use an alpha channel in the font rasterizer

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This commit is contained in:
Romain Goyet
2015-05-13 19:31:19 +02:00
parent 09de7fc8cb
commit 2924361b15
1 changed files with 10 additions and 10 deletions
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20
fonts/rasterizer.c
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@@ -18,13 +18,12 @@
#define ENSURE(action, description...) { if (!(action)) { fprintf(stderr, "Error: "); fprintf(stderr, description); fprintf(stderr, "\n"); exit(-1);}}
// Pixel format is BGRA8888
// Pixel format is RGB888
typedef struct {
char blue;
char green;
char red;
char alpha;
char green;
char blue;
} pixel_t;
typedef struct {
@@ -65,12 +64,14 @@ int main(int argc, char * argv[]) {
bitmap_image.pixels = malloc(sizeof(pixel_t)*bitmap_image.width*bitmap_image.height);
ENSURE(bitmap_image.pixels != NULL, "Allocating bitmap image of size %dx%d at %ld bytes per pixel", glyph_width*16, glyph_height*16, sizeof(pixel_t));
// Draw the grid
// Draw the grid and the background
for (int i = 0; i<bitmap_image.width;i++) {
for (int j = 0; j<bitmap_image.height;j++) {
pixel_t pixel = {.red = 0xFF, .green = 0xFF, .blue = 0xFF};
if (i%(glyph_width+grid_size) >= glyph_width || j%(glyph_height+grid_size) >= glyph_height) {
*(bitmap_image.pixels + j*bitmap_image.width + i) = (pixel_t){.red = 0xFF, .green = 0, .blue = 0, .alpha = 0xFF};
pixel = (pixel_t){.red = 0xFF, .green = 0, .blue = 0};
}
*(bitmap_image.pixels + j*bitmap_image.width + i) = pixel;
}
}
@@ -106,7 +107,8 @@ void drawGlyphInImage(FT_Bitmap * glyphBitmap, image_t * image, int x, int y) {
for (int j=0;j<glyphBitmap->rows;j++) {
for (int i=0;i<glyphBitmap->width;i++) {
uint8_t glyphPixel = *(glyphBitmap->buffer + j*glyphBitmap->pitch + i);
*(image->pixels + (y+j)*image->width + (x+i)) = (pixel_t){.alpha = glyphPixel};
pixel_t * currentPixelPointer = (image->pixels + (y+j)*image->width + (x+i));
*currentPixelPointer = (pixel_t){.red = (0xFF-glyphPixel), .green = (0xFF-glyphPixel), .blue = (0xFF-glyphPixel)}; // Alpha blending
}
}
}
@@ -120,8 +122,6 @@ void writeImageToPNGFile(image_t * image, char * filename) {
png_structp png = png_create_write_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
ENSURE(png != NULL, "Allocating PNG write structure");
png_set_bgr(png); // Our pixel_t is BGRA
png_infop info = png_create_info_struct(png);
ENSURE(info != NULL, "Allocating info structure");
@@ -130,7 +130,7 @@ void writeImageToPNGFile(image_t * image, char * filename) {
png_set_IHDR(png, info,
image->width, image->height,
8, // Number of bits per channel
PNG_COLOR_TYPE_RGB_ALPHA, // RGBA
PNG_COLOR_TYPE_RGB,
PNG_INTERLACE_NONE,
PNG_COMPRESSION_TYPE_DEFAULT,
PNG_FILTER_TYPE_DEFAULT);