Add example/sdl-imageviewer
diff --git a/build-example.sh b/build-example.sh
index 8c48e2e..96c4a62 100755
--- a/build-example.sh
+++ b/build-example.sh
@@ -42,7 +42,11 @@
if [ $f = imageviewer ]; then
# example/imageviewer is unusual in that needs additional libraries.
echo "Building gen/bin/example-$f"
- $CXX -O3 example/$f/*.cc -lxcb -lxcb-image -o gen/bin/example-$f
+ $CXX -O3 example/$f/*.cc -lxcb -lxcb-image -o gen/bin/example-$f
+ elif [ $f = "sdl-imageviewer" ]; then
+ # example/sdl-imageviewer is unusual in that needs additional libraries.
+ echo "Building gen/bin/example-$f"
+ $CXX -O3 example/$f/*.cc -lSDL2 -lSDL2_image -o gen/bin/example-$f
elif [ $f = "toy-genlib" ]; then
# example/toy-genlib is unusual in that it uses separately compiled
# libraries (built by "wuffs genlib", e.g. by running build-all.sh) instead
diff --git a/example/sdl-imageviewer/sdl-imageviewer.cc b/example/sdl-imageviewer/sdl-imageviewer.cc
new file mode 100644
index 0000000..d220a36
--- /dev/null
+++ b/example/sdl-imageviewer/sdl-imageviewer.cc
@@ -0,0 +1,357 @@
+// Copyright 2021 The Wuffs Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// ----------------
+
+/*
+sdl-imageviewer is a simple GUI program for viewing an image. To run:
+
+$CXX sdl-imageviewer.cc -lSDL2 -lSDL2_image && \
+ ./a.out ../../test/data/bricks-color.png; rm -f a.out
+
+for a C++ compiler $CXX, such as clang++ or g++.
+
+The Tab key switches between decoding the image via Wuffs or via SDL2_image.
+There should be no difference unless you uncomment the § line of code below.
+
+The Escape key quits.
+
+----
+
+This program (in Wuffs' example directory) is like example/imageviewer but with
+fewer features. It focuses on showing how to integrate the Wuffs image decoders
+with SDL (as an alternative to the SDL_image extension).
+
+While SDL is cross-platform, this program is not as good as example/imageviewer
+for general use. SDL (which is designed for full-screen games) uses a noticable
+amount of CPU (and therefore power) polling for events even when the program
+isn't otherwise doing anything.
+*/
+
+#include <inttypes.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+// Wuffs ships as a "single file C library" or "header file library" as per
+// https://github.com/nothings/stb/blob/master/docs/stb_howto.txt
+//
+// To use that single file as a "foo.c"-like implementation, instead of a
+// "foo.h"-like header, #define WUFFS_IMPLEMENTATION before #include'ing or
+// compiling it.
+#define WUFFS_IMPLEMENTATION
+
+// Defining the WUFFS_CONFIG__MODULE* macros are optional, but it lets users of
+// release/c/etc.c choose which parts of Wuffs to build. That file contains the
+// entire Wuffs standard library, implementing a variety of codecs and file
+// formats. Without this macro definition, an optimizing compiler or linker may
+// very well discard Wuffs code for unused codecs, but listing the Wuffs
+// modules we use makes that process explicit. Preprocessing means that such
+// code simply isn't compiled.
+#define WUFFS_CONFIG__MODULES
+#define WUFFS_CONFIG__MODULE__ADLER32
+#define WUFFS_CONFIG__MODULE__AUX__BASE
+#define WUFFS_CONFIG__MODULE__AUX__IMAGE
+#define WUFFS_CONFIG__MODULE__BASE
+#define WUFFS_CONFIG__MODULE__BMP
+#define WUFFS_CONFIG__MODULE__CRC32
+#define WUFFS_CONFIG__MODULE__DEFLATE
+#define WUFFS_CONFIG__MODULE__GIF
+#define WUFFS_CONFIG__MODULE__LZW
+#define WUFFS_CONFIG__MODULE__PNG
+#define WUFFS_CONFIG__MODULE__ZLIB
+
+// If building this program in an environment that doesn't easily accommodate
+// relative includes, you can use the script/inline-c-relative-includes.go
+// program to generate a stand-alone C file.
+#include "../../release/c/wuffs-unsupported-snapshot.c"
+
+// ----------------
+
+#include <SDL2/SDL.h>
+#include <SDL2/SDL_image.h>
+
+// --------
+
+class Wuffs_Load_RW_Callbacks : public wuffs_aux::DecodeImageCallbacks {
+ public:
+ Wuffs_Load_RW_Callbacks(SDL_PixelFormat* pixfmt)
+ : m_rmask(pixfmt->Rmask),
+ m_gmask(pixfmt->Gmask),
+ m_bmask(pixfmt->Bmask),
+ m_amask(0xFFFFFFFFu ^ pixfmt->Rmask ^ pixfmt->Gmask ^ pixfmt->Bmask),
+ m_surface(NULL) {}
+
+ ~Wuffs_Load_RW_Callbacks() {
+ if (m_surface) {
+ SDL_UnlockSurface(m_surface);
+ SDL_FreeSurface(m_surface);
+ m_surface = NULL;
+ }
+ }
+
+ SDL_Surface* //
+ TakeSurface() {
+ if (!m_surface) {
+ return NULL;
+ }
+ SDL_UnlockSurface(m_surface);
+ SDL_Surface* ret = m_surface;
+ m_surface = NULL;
+ return ret;
+ }
+
+ private:
+ wuffs_base__pixel_format //
+ SelectPixfmt(const wuffs_base__image_config& image_config) override {
+#if SDL_BYTEORDER == SDL_BIG_ENDIAN
+ bool red_first = (m_rmask)&0x80000000u;
+#else
+ bool red_first = (m_rmask)&0x00000001u;
+#endif
+
+ // (§) Uncomment this line of code to invert the BGRA/RGBA color order.
+ // This isn't a generally useful feature for an image viewer, but it should
+ // make it obvious, when pressing the TAB key, whether you're using the
+ // Wuffs (inverted) or SDL_image (correct) decoder.
+ //
+ // red_first = !red_first;
+
+ wuffs_base__pixel_format pixfmt = wuffs_base__make_pixel_format(
+ red_first ? WUFFS_BASE__PIXEL_FORMAT__RGBA_NONPREMUL
+ : WUFFS_BASE__PIXEL_FORMAT__BGRA_NONPREMUL);
+ return pixfmt;
+ }
+
+ AllocResult //
+ AllocPixbuf(const wuffs_base__image_config& image_config,
+ bool allow_uninitialized_memory) override {
+ if (m_surface) {
+ SDL_UnlockSurface(m_surface);
+ SDL_FreeSurface(m_surface);
+ m_surface = NULL;
+ }
+ uint32_t w = image_config.pixcfg.width();
+ uint32_t h = image_config.pixcfg.height();
+ if ((w > 0xFFFFFF) || (h > 0xFFFFFF)) {
+ return AllocResult("Wuffs_Load_RW_Callbacks: image is too large");
+ }
+ m_surface =
+ SDL_CreateRGBSurface(0, static_cast<int>(w), static_cast<int>(h), 32,
+ m_rmask, m_gmask, m_bmask, m_amask);
+ if (!m_surface) {
+ return AllocResult(
+ "Wuffs_Load_RW_Callbacks: SDL_CreateRGBSurface failed");
+ }
+ SDL_LockSurface(m_surface);
+ return AllocResult(
+ wuffs_aux::MemOwner(NULL, &free),
+ wuffs_base__make_slice_u8(static_cast<uint8_t*>(m_surface->pixels),
+ m_surface->h * m_surface->pitch));
+ }
+
+ const uint32_t m_rmask;
+ const uint32_t m_gmask;
+ const uint32_t m_bmask;
+ const uint32_t m_amask;
+ SDL_Surface* m_surface;
+};
+
+// --------
+
+class Wuffs_Load_RW_Input : public wuffs_aux::sync_io::Input {
+ public:
+ Wuffs_Load_RW_Input(SDL_RWops* rw, bool take_ownership_of_rw)
+ : m_rw(rw), m_ownership(take_ownership_of_rw) {}
+
+ ~Wuffs_Load_RW_Input() {
+ if (m_rw && m_ownership) {
+ m_rw->close(m_rw);
+ }
+ }
+
+ private:
+ std::string //
+ CopyIn(wuffs_aux::IOBuffer* dst) override {
+ if (!m_rw) {
+ return "Wuffs_Load_RW_Input: NULL SDL_RWops";
+ } else if (!dst) {
+ return "Wuffs_Load_RW_Input: NULL IOBuffer";
+ } else if (dst->meta.closed) {
+ return "Wuffs_Load_RW_Input: end of file";
+ }
+ dst->compact();
+ if (dst->writer_length() == 0) {
+ return "Wuffs_Load_RW_Input: full IOBuffer";
+ }
+ size_t n = m_rw->read(m_rw, dst->writer_pointer(), 1, dst->writer_length());
+ dst->meta.wi += n;
+ return std::string();
+ }
+
+ SDL_RWops* m_rw;
+ const bool m_ownership;
+};
+
+// --------
+
+// Wuffs_Load_RW loads the image from the given file into the given format
+// (which must be 32-bits per pixel). It is similar to SDL_image's IMG_Load_RW
+// function but it returns any error in-band (as a std::string) instead of
+// separately (global state accessible via SDL_GetError).
+//
+// On success, the SDL_Surface* returned will be non-NULL and the caller owns
+// it. Ownership means that they are responsible for calling SDL_FreeSurface on
+// it when done.
+std::pair<SDL_Surface*, std::string> //
+Wuffs_Load_RW(SDL_RWops* rw,
+ bool take_ownership_of_rw,
+ SDL_PixelFormat* format) {
+ Wuffs_Load_RW_Input input(rw, take_ownership_of_rw);
+
+ if (!format || (format->BitsPerPixel != 32)) {
+ return std::make_pair<SDL_Surface*, std::string>(
+ NULL, "Wuffs_Load_RW: invalid pixel format");
+ }
+ Wuffs_Load_RW_Callbacks callbacks(format);
+
+ wuffs_aux::DecodeImageResult res = wuffs_aux::DecodeImage(callbacks, input);
+ if (!res.error_message.empty()) {
+ return std::make_pair<SDL_Surface*, std::string>(
+ NULL, std::move(res.error_message));
+ }
+ return std::make_pair<SDL_Surface*, std::string>(callbacks.TakeSurface(),
+ std::string());
+}
+
+// ----------------
+
+SDL_Surface* g_image = NULL;
+bool g_load_via_sdl_image = false;
+
+bool //
+draw(SDL_Window* window) {
+ SDL_Surface* ws = SDL_GetWindowSurface(window);
+ SDL_FillRect(ws, NULL, SDL_MapRGB(ws->format, 0x00, 0x00, 0x00));
+ if (g_image) {
+ SDL_BlitSurface(g_image, NULL, ws, NULL);
+ }
+ SDL_UpdateWindowSurface(window);
+ return true;
+}
+
+bool //
+load_image(SDL_Window* window, const char* filename) {
+ if (g_image) {
+ SDL_FreeSurface(g_image);
+ g_image = NULL;
+ }
+
+ SDL_RWops* rw = SDL_RWFromFile(filename, "rb");
+ if (!rw) {
+ fprintf(stderr, "main: SDL_RWFromFile(\"%s\"): %s\n", filename,
+ SDL_GetError());
+ return false;
+ }
+
+ constexpr bool take_ownership_of_rw = true;
+ if (g_load_via_sdl_image) {
+ g_image = IMG_Load_RW(rw, take_ownership_of_rw);
+ if (!g_image) {
+ fprintf(stderr, "main: IMG_Load_RW(\"%s\"): %s\n", filename,
+ SDL_GetError());
+ return false;
+ }
+ } else {
+ std::pair<SDL_Surface*, std::string> p = Wuffs_Load_RW(
+ rw, take_ownership_of_rw, SDL_GetWindowSurface(window)->format);
+ if (!p.second.empty()) {
+ fprintf(stderr, "main: Wuffs_Load_RW(\"%s\"): %s\n", filename,
+ p.second.c_str());
+ return false;
+ }
+ g_image = p.first;
+ }
+
+ return true;
+}
+
+int //
+main(int argc, char** argv) {
+ if (argc != 2) {
+ fprintf(stderr, "usage: %s filename\n", argv[0]);
+ return 1;
+ }
+ if (SDL_Init(SDL_INIT_VIDEO) < 0) {
+ fprintf(stderr, "main: SDL_Init: %s\n", SDL_GetError());
+ return 1;
+ }
+ SDL_Window* window =
+ SDL_CreateWindow("sdl-imageviewer", SDL_WINDOWPOS_UNDEFINED,
+ SDL_WINDOWPOS_UNDEFINED, 1024, 768, SDL_WINDOW_SHOWN);
+ if (!window) {
+ fprintf(stderr, "main: SDL_CreateWindow: %s\n", SDL_GetError());
+ return 1;
+ }
+
+ if (!load_image(window, argv[1])) {
+ return 1;
+ }
+
+ while (true) {
+ SDL_Event event;
+ if (!SDL_WaitEvent(&event)) {
+ fprintf(stderr, "main: SDL_WaitEvent: %s\n", SDL_GetError());
+ return 1;
+ }
+
+ switch (event.type) {
+ case SDL_QUIT:
+ goto cleanup;
+
+ case SDL_WINDOWEVENT:
+ switch (event.window.event) {
+ case SDL_WINDOWEVENT_EXPOSED:
+ if (!draw(window)) {
+ return 1;
+ }
+ break;
+ }
+ break;
+
+ case SDL_KEYDOWN:
+ switch (event.key.keysym.sym) {
+ case SDLK_ESCAPE:
+ goto cleanup;
+ case SDLK_TAB:
+ g_load_via_sdl_image = !g_load_via_sdl_image;
+ printf("Switched to %s.\n",
+ g_load_via_sdl_image ? "SDL_image" : "Wuffs");
+ if (!load_image(window, argv[1]) || !draw(window)) {
+ return 1;
+ }
+ break;
+ }
+ break;
+ }
+ }
+
+cleanup:
+ if (g_image) {
+ SDL_FreeSurface(g_image);
+ g_image = NULL;
+ }
+ SDL_DestroyWindow(window);
+ SDL_Quit();
+ return 0;
+}
