Fix high-DPI scaling in sdl_renderer

This commit resolves two issues with high-DPI display rendering:

1. The coordinates were not scaled properly, resulting in tiny output
   and misalignment of actual cursor position with apparent position;
   this is fixed by calling SDL_SetRenderScale with appropriate scaling
   factors determined by comparing the window size to the renderer's
   output size
2. The fonts were not oversampled, resulting in excessively blurry text;
    this is fixed by setting oversample_h and oversample_v on the
    font_config according to the scaling factors
This commit is contained in:
Kristian Bolino 2022-03-14 12:26:25 -04:00
parent cbfc8f89e9
commit ec4aa9992f

View File

@ -76,6 +76,8 @@ main(int argc, char *argv[])
SDL_Renderer *renderer; SDL_Renderer *renderer;
int running = 1; int running = 1;
int flags = 0; int flags = 0;
unsigned char oversample_h = 1;
unsigned char oversample_v = 1;
/* GUI */ /* GUI */
struct nk_context *ctx; struct nk_context *ctx;
@ -112,22 +114,53 @@ main(int argc, char *argv[])
exit(-1); exit(-1);
} }
/* scale the renderer output for High-DPI displays */
{
int render_w, render_h;
int window_w, window_h;
float scale_x, scale_y;
SDL_GetRendererOutputSize(renderer, &render_w, &render_h);
SDL_GetWindowSize(win, &window_w, &window_h);
scale_x = (float)(render_w) / (float)(window_w);
scale_y = (float)(render_h) / (float)(window_h);
SDL_RenderSetScale(renderer, scale_x, scale_y);
if (scale_x > 1) {
oversample_h = nk_iceilf(scale_x);
}
if (scale_y > 1) {
oversample_v = nk_iceilf(scale_y);
}
}
/* GUI */ /* GUI */
ctx = nk_sdl_init(win, renderer); ctx = nk_sdl_init(win, renderer);
/* Load Fonts: if none of these are loaded a default font will be used */ /* Load Fonts: if none of these are loaded a default font will be used */
/* Load Cursor: if you uncomment cursor loading please hide the cursor */ /* Load Cursor: if you uncomment cursor loading please hide the cursor */
{struct nk_font_atlas *atlas; {
nk_sdl_font_stash_begin(&atlas); struct nk_font_atlas *atlas;
/*struct nk_font *droid = nk_font_atlas_add_from_file(atlas, "../../../extra_font/DroidSans.ttf", 14, 0);*/ struct nk_font_config config = nk_font_config(0);
/*struct nk_font *roboto = nk_font_atlas_add_from_file(atlas, "../../../extra_font/Roboto-Regular.ttf", 16, 0);*/
/*struct nk_font *future = nk_font_atlas_add_from_file(atlas, "../../../extra_font/kenvector_future_thin.ttf", 13, 0);*/ /* oversample the fonts for high-DPI displays */
/*struct nk_font *clean = nk_font_atlas_add_from_file(atlas, "../../../extra_font/ProggyClean.ttf", 12, 0);*/ if (oversample_h > 1) {
/*struct nk_font *tiny = nk_font_atlas_add_from_file(atlas, "../../../extra_font/ProggyTiny.ttf", 10, 0);*/ config.oversample_h = oversample_h;
/*struct nk_font *cousine = nk_font_atlas_add_from_file(atlas, "../../../extra_font/Cousine-Regular.ttf", 13, 0);*/ }
nk_sdl_font_stash_end(); if (oversample_v > 1) {
/*nk_style_load_all_cursors(ctx, atlas->cursors);*/ config.oversample_v = oversample_v;
/*nk_style_set_font(ctx, &roboto->handle)*/;} }
/* set up the font atlas and add desired fonts */
nk_sdl_font_stash_begin(&atlas);
struct nk_font *default_font = nk_font_atlas_add_default(atlas, 12, &config);
/*struct nk_font *droid = nk_font_atlas_add_from_file(atlas, "../../../extra_font/DroidSans.ttf", 14, &config);*/
/*struct nk_font *roboto = nk_font_atlas_add_from_file(atlas, "../../../extra_font/Roboto-Regular.ttf", 16, &config);*/
/*struct nk_font *future = nk_font_atlas_add_from_file(atlas, "../../../extra_font/kenvector_future_thin.ttf", 13, &config);*/
/*struct nk_font *clean = nk_font_atlas_add_from_file(atlas, "../../../extra_font/ProggyClean.ttf", 12, &config);*/
/*struct nk_font *tiny = nk_font_atlas_add_from_file(atlas, "../../../extra_font/ProggyTiny.ttf", 10, &config);*/
/*struct nk_font *cousine = nk_font_atlas_add_from_file(atlas, "../../../extra_font/Cousine-Regular.ttf", 13, &config);*/
nk_sdl_font_stash_end();
/*nk_style_load_all_cursors(ctx, atlas->cursors);*/
nk_style_set_font(ctx, &default_font->handle);
}
#ifdef INCLUDE_STYLE #ifdef INCLUDE_STYLE
/*set_style(ctx, THEME_WHITE);*/ /*set_style(ctx, THEME_WHITE);*/
@ -212,4 +245,3 @@ cleanup:
SDL_Quit(); SDL_Quit();
return 0; return 0;
} }