From 219f18f30df465beeee8114febe52fa50454a804 Mon Sep 17 00:00:00 2001 From: halcanary Date: Tue, 1 Sep 2015 10:01:38 -0700 Subject: C API: Add SK_API, also documentation of an example. SK_API = __declspec(dllexport) / __attribute__((visibility("default"))) Also, add documentation in experimental/c-api-example/c.md Review URL: https://codereview.chromium.org/1307183006 --- experimental/c-api-example/c.md | 174 ++++++++++++++++++++++++++++ experimental/c-api-example/skia-c-example.c | 81 +++++++++++++ 2 files changed, 255 insertions(+) create mode 100644 experimental/c-api-example/c.md create mode 100644 experimental/c-api-example/skia-c-example.c (limited to 'experimental/c-api-example') diff --git a/experimental/c-api-example/c.md b/experimental/c-api-example/c.md new file mode 100644 index 0000000000..1647a6f9d3 --- /dev/null +++ b/experimental/c-api-example/c.md @@ -0,0 +1,174 @@ +Skia's Stable C API +=================== + +
+EXPERIMENTAL EXPERIMENTAL EXPERIMENTAL EXPERIMENTAL
+DO NOT USE — FOR INTERNAL TESTING ONLY +
+ +Several issues hinder the development of a stable ABI (application +binary interface) for Skia: + +1. Skia's C++ API changes a lot from version to version. Skia's two + largest clients, Android and Chrome, are kept up to date by the + Skia team, but that can not happen for every client. +2. Skia's headers will only match the compiled skia libraries if + configured identically. + +To mitigate these two issues, Skia is experimenting with the +introduction of a C API. This will change more slowly than the C++ +interface and, once API version 1.0.0 is announced, +backwards-incompatable changes will be avoided whenever possible. + +Here is an example program that uses the C api. To try it out, get the file +[`skia-c-example.c`](./skia-c-example.c). + + + + #include + + #include "sk_data.h" + #include "sk_image.h" + #include "sk_canvas.h" + #include "sk_surface.h" + #include "sk_paint.h" + #include "sk_path.h" + + static sk_surface_t* make_surface(int32_t w, int32_t h) { + sk_imageinfo_t info; + info.width = w; + info.height = h; + info.colorType = sk_colortype_get_default_8888(); + info.alphaType = PREMUL_SK_ALPHATYPE; + return sk_surface_new_raster(&info, NULL); + } + + static void emit_png(const char* path, sk_surface_t* surface) { + sk_image_t* image = sk_surface_new_image_snapshot(surface); + sk_data_t* data = sk_image_encode(image); + sk_image_unref(image); + FILE* f = fopen(path, "wb"); + fwrite(sk_data_get_data(data), sk_data_get_size(data), 1, f); + fclose(f); + sk_data_unref(data); + } + + void draw(sk_canvas_t* canvas) { + sk_paint_t* fill = sk_paint_new(); + sk_paint_set_color(fill, sk_color_set_argb(0xFF, 0x00, 0x00, 0xFF)); + sk_canvas_draw_paint(canvas, fill); + + sk_paint_set_color(fill, sk_color_set_argb(0xFF, 0x00, 0xFF, 0xFF)); + sk_rect_t rect; + rect.left = 100.0f; + rect.top = 100.0f; + rect.right = 540.0f; + rect.bottom = 380.0f; + sk_canvas_draw_rect(canvas, &rect, fill); + + sk_paint_t* stroke = sk_paint_new(); + sk_paint_set_color(stroke, sk_color_set_argb(0xFF, 0xFF, 0x00, 0x00)); + sk_paint_set_antialias(stroke, true); + sk_paint_set_stroke(stroke, true); + sk_paint_set_stroke_width(stroke, 5.0f); + sk_path_t* path = sk_path_new(); + + sk_path_move_to(path, 50.0f, 50.0f); + sk_path_line_to(path, 590.0f, 50.0f); + sk_path_cubic_to(path, -490.0f, 50.0f, 1130.0f, 430.0f, 50.0f, 430.0f); + sk_path_line_to(path, 590.0f, 430.0f); + sk_canvas_draw_path(canvas, path, stroke); + + sk_paint_set_color(fill, sk_color_set_argb(0x80, 0x00, 0xFF, 0x00)); + sk_rect_t rect2; + rect2.left = 120.0f; + rect2.top = 120.0f; + rect2.right = 520.0f; + rect2.bottom = 360.0f; + sk_canvas_draw_oval(canvas, &rect2, fill); + + sk_path_delete(path); + sk_paint_delete(stroke); + sk_paint_delete(fill); + } + + int main() { + sk_surface_t* surface = make_surface(640, 480); + sk_canvas_t* canvas = sk_surface_get_canvas(surface); + draw(canvas); + emit_png("skia-c-example.png", surface); + sk_surface_unref(surface); + return 0; + } + + + +Gyp+Linux example +----------------- + +The following proof-of-concept workflow currently works on Ubuntu 14.04: + +1. Aquire Skia and install dependencies (you may have already done this): + + + + git clone 'https://chromium.googlesource.com/chromium/tools/depot_tools.git' + export PATH="$PWD/depot_tools:$PATH" + git clone 'https://skia.googlesource.com/skia' + skia/tools/install_dependencies.sh + SKIA_DIR="$PWD/skia" + +2. Compile Skia as a shared library: + + + + GYP_DEFINES=skia_shared_lib=1 "$SKIA_DIR"/bin/sync-and-gyp + ninja -C "$SKIA_DIR/out/Release" skia_lib + +3. Compile, link, and run the example program: + + + + cd [Wherever you want the example] + cp "$SKIA_DIR/experimental/c-api-example/skia-c-example.c" . + cc -c -I "$SKIA_DIR/include/c" skia-c-example.c -o skia-c-example.o + cc skia-c-example.o -L "$SKIA_DIR/out/Release/lib" -lskia -o skia-c-example + LD_LIBRARY_PATH="$SKIA_DIR/out/Release/lib" ./skia-c-example + xdg-open skia-c-example.png + +Cmake+MacOS example +------------------- + +The following proof-of-concept workflow currently works on MacOS + +1. Aquire Skia and install dependencies (you may have already done this): + + + + cd [Wherever you want skia src code] + git clone 'https://skia.googlesource.com/skia' + SKIA_DIR="$PWD/skia" + +2. Compile Skia as a shared library: + + + + cd [Wherever you want skia build files] + mkdir build_skia + cd build_skia + SKIA_BUILD="$PWD" + cmake "$SKIA_DIR/cmake" -G Ninja && ninja + +3. Compile, link, and run the example program: + + + + cd [Wherever you want the example] + cp "$SKIA_DIR/experimental/c-api-example/skia-c-example.c" . + cc -c -I "$SKIA_DIR/include/c" skia-c-example.c -o skia-c-example.o + c++ skia-c-example.o \ + "$SKIA_BUILD"/libskia.* -Wl,-rpath -Wl,"$SKIA_BUILD" \ + -o skia-c-example + ./skia-c-example + open skia-c-example.png diff --git a/experimental/c-api-example/skia-c-example.c b/experimental/c-api-example/skia-c-example.c new file mode 100644 index 0000000000..66b17fc006 --- /dev/null +++ b/experimental/c-api-example/skia-c-example.c @@ -0,0 +1,81 @@ +/* + * Copyright 2015 Google Inc. + * + * Use of this source code is governed by a BSD-style license that can be + * found in the LICENSE file. + */ +#include + +#include "sk_data.h" +#include "sk_image.h" +#include "sk_canvas.h" +#include "sk_surface.h" +#include "sk_paint.h" +#include "sk_path.h" + +static sk_surface_t* make_surface(int32_t w, int32_t h) { + sk_imageinfo_t info; + info.width = w; + info.height = h; + info.colorType = sk_colortype_get_default_8888(); + info.alphaType = PREMUL_SK_ALPHATYPE; + return sk_surface_new_raster(&info, NULL); +} + +static void emit_png(const char* path, sk_surface_t* surface) { + sk_image_t* image = sk_surface_new_image_snapshot(surface); + sk_data_t* data = sk_image_encode(image); + sk_image_unref(image); + FILE* f = fopen(path, "wb"); + fwrite(sk_data_get_data(data), sk_data_get_size(data), 1, f); + fclose(f); + sk_data_unref(data); +} + +void draw(sk_canvas_t* canvas) { + sk_paint_t* fill = sk_paint_new(); + sk_paint_set_color(fill, sk_color_set_argb(0xFF, 0x00, 0x00, 0xFF)); + sk_canvas_draw_paint(canvas, fill); + + sk_paint_set_color(fill, sk_color_set_argb(0xFF, 0x00, 0xFF, 0xFF)); + sk_rect_t rect; + rect.left = 100.0f; + rect.top = 100.0f; + rect.right = 540.0f; + rect.bottom = 380.0f; + sk_canvas_draw_rect(canvas, &rect, fill); + + sk_paint_t* stroke = sk_paint_new(); + sk_paint_set_color(stroke, sk_color_set_argb(0xFF, 0xFF, 0x00, 0x00)); + sk_paint_set_antialias(stroke, true); + sk_paint_set_stroke(stroke, true); + sk_paint_set_stroke_width(stroke, 5.0f); + sk_path_t* path = sk_path_new(); + + sk_path_move_to(path, 50.0f, 50.0f); + sk_path_line_to(path, 590.0f, 50.0f); + sk_path_cubic_to(path, -490.0f, 50.0f, 1130.0f, 430.0f, 50.0f, 430.0f); + sk_path_line_to(path, 590.0f, 430.0f); + sk_canvas_draw_path(canvas, path, stroke); + + sk_paint_set_color(fill, sk_color_set_argb(0x80, 0x00, 0xFF, 0x00)); + sk_rect_t rect2; + rect2.left = 120.0f; + rect2.top = 120.0f; + rect2.right = 520.0f; + rect2.bottom = 360.0f; + sk_canvas_draw_oval(canvas, &rect2, fill); + + sk_path_delete(path); + sk_paint_delete(stroke); + sk_paint_delete(fill); +} + +int main() { + sk_surface_t* surface = make_surface(640, 480); + sk_canvas_t* canvas = sk_surface_get_canvas(surface); + draw(canvas); + emit_png("skia-c-example.png", surface); + sk_surface_unref(surface); + return 0; +} -- cgit v1.2.3