ad8e/glfw_ship.cpp

## glfw_ship.cpp
/* Note: this Google copyright notice only applies to the original file, which has large sections copy-pasted here. my changes are under CC0 (public domain).

 * Copyright 2015 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

/*
The official instructions don't work well. These alternative instructions are intended to be the shortest path to get a minimal setup running.
The Linux steps were run through successfully on Sept 2023.
The Windows steps are known to be broken; the broken part is Step 7. The Include and Library directories should be tweaked.

This was made by copy-pasting and fixing two sources: https://github.com/google/skia/tree/master/experimental/GLFWTest and https://gist.github.com/zester/5163313
Don't bother trying these two sources; neither of them works.


step 1: install glfw (on Linux, "sudo apt install libglfw3-dev" will get you an acceptable (and outdated) version. on Visual Studio, you can get glfw from vcpkg.)
step 2: follow https://skia.org/docs/user/download/ to download and build skia.
Move forward to either Windows step 6 or Linux step 6.

Windows step 6, Visual Studio 2017:
if you're in Windows, you will need to use bash (tested as of 2017; haven't tried recently). on my system, a copy of bash came with my installation of Git for Windows.
cmd.exe doesn't allow single quotes, which are necessary to give the VC path. the various skia_use_foo commands are necessary to stop VS from erroring out when the headers are missing
run these two commands, replacing "C:\Program Files (x86)\Microsoft Visual Studio\2017\Community\VC" with your own VC directory:
gn gen out/Static --args='is_official_build=true win_vc="C:\Program Files (x86)\Microsoft Visual Studio\2017\Community\VC" skia_use_libpng=false skia_use_zlib=false skia_use_libwebp=false skia_enable_pdf=false skia_use_libjpeg_turbo=false skia_use_expat=false'
ninja -C out/Static

Windows step 7. Warning, this is outdated. The massive "FOLDER1\x" was changed to not be necessary, but I haven't tested the correct steps now:
add this file to a new VS project
append "FOLDER1\skia\include\core;FOLDER1\skia\include\gpu;FOLDER1\skia\include\config;FOLDER1\skia\include\utils;FOLDER2\glfw\include'" to the VC include directories of your project, where FOLDERX represents the directories you put them in.
	you must include all 4 skia folders because the files inside skia folders assume they see the other folders.
	if you're unfamiliar with how the include directory works, it's in Project->Properties, VC++ Directories, Include Directories.
append "FOLDER1\skia\out\Static;FOLDER2\glfw\src\Debug;" to Library Directories, again replacing FOLDERX with the true location. add "opengl32.lib;skia.lib;glfw3.lib;" to Linker->Input->Additional Dependencies
Set build mode to x64.
Build! This will produce a debug mode binary.
If in the future you want a release mode binary, you will need to re-build glfw in release mode, and change the glfw library folder to FOLDER2\glfw\src\Release;

Linux step 6, Ubuntu 23.04. Sept 3, 2023:
Run:
sudo apt install clang libjpeg-dev libicu-dev libwebp-dev libfontconfig-dev
bin/gn gen out/Static --args='is_official_build=true cc="clang" cxx="clang++"'
ninja -C out/Static

Linux step 7:
download this file as "glfw_ship.cpp", and place it in the parent folder of the "skia" directory. (this just makes "-Iskia" in the right place)
g++ -g -std=c++1z glfw_ship.cpp -lskia -ldl -lpthread -ljpeg -lfreetype -lz -lpng -lglfw -lfontconfig -lwebp -lwebpmux -lwebpdemux -lGL -Iskia -Lskia/out/Static/
./a.out


eventually, you will want color-correct spaces, and there are 5 places below (Ctrl+F "enable correct color spaces"), where you should replace/uncomment lines to enable this.
warning: color-correct spaces don't work in VMWare, because mesa doesn't support it.
*/

#include "GLFW/glfw3.h"
#define SK_GANESH
#define SK_GL
#include "include/gpu/GrBackendSurface.h"
#include "include/gpu/GrDirectContext.h"
#include "include/gpu/gl/GrGLInterface.h"
#include "include/gpu/gl/GrGLAssembleInterface.h"
#include "include/gpu/ganesh/SkSurfaceGanesh.h"
#include "include/gpu/ganesh/gl/GrGLBackendSurface.h"
#include "include/core/SkCanvas.h"
#include "include/core/SkColorSpace.h"
#include "include/core/SkSurface.h"

#include <stdio.h>
#include <stdlib.h>

//uncomment the two lines below to enable correct color spaces
//#define GL_FRAMEBUFFER_SRGB 0x8DB9
//#define GL_SRGB8_ALPHA8 0x8C43

GrDirectContext* sContext = nullptr;
SkSurface* sSurface = nullptr;

void error_callback(int error, const char* description) {
	fputs(description, stderr);
}

void key_callback(GLFWwindow* window, int key, int scancode, int action, int mods) {
	if (key == GLFW_KEY_ESCAPE && action == GLFW_PRESS)
		glfwSetWindowShouldClose(window, GL_TRUE);
}

void init_skia(int w, int h) {
	auto interface = GrGLMakeNativeInterface();
	if (interface == nullptr) {
		//backup plan. see https://gist.github.com/ad8e/dd150b775ae6aa4d5cf1a092e4713add?permalink_comment_id=4680136#gistcomment-4680136
		interface = GrGLMakeAssembledInterface(
			nullptr, (GrGLGetProc) * [](void*, const char* p) -> void* { return (void*)glfwGetProcAddress(p); });
	}
	sContext = GrDirectContext::MakeGL(interface).release();

	GrGLFramebufferInfo framebufferInfo;
	framebufferInfo.fFBOID = 0; // assume default framebuffer
	// We are always using OpenGL and we use RGBA8 internal format for both RGBA and BGRA configs in OpenGL.
	//(replace line below with this one to enable correct color spaces) framebufferInfo.fFormat = GL_SRGB8_ALPHA8;
	framebufferInfo.fFormat = GL_RGBA8;

	SkColorType colorType = kRGBA_8888_SkColorType;
	GrBackendRenderTarget backendRenderTarget = GrBackendRenderTargets::MakeGL(w, h,
		0, // sample count
		0, // stencil bits
		framebufferInfo);

	//(replace line below with this one to enable correct color spaces) sSurface = SkSurfaces::WrapBackendRenderTarget(sContext, backendRenderTarget, kBottomLeft_GrSurfaceOrigin, colorType, SkColorSpace::MakeSRGB(), nullptr).release();
	sSurface = SkSurfaces::WrapBackendRenderTarget(sContext, backendRenderTarget, kBottomLeft_GrSurfaceOrigin, colorType, nullptr, nullptr).release();
	if (sSurface == nullptr) abort();
}

void cleanup_skia() {
	delete sSurface;
	delete sContext;
}

const int kWidth = 960;
const int kHeight = 640;

int main(void) {
	GLFWwindow* window;
	glfwSetErrorCallback(error_callback);
	if (!glfwInit()) {
		exit(EXIT_FAILURE);
	}

	glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
	glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 2);
	glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE);
	glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
	//(uncomment to enable correct color spaces) glfwWindowHint(GLFW_SRGB_CAPABLE, GL_TRUE);
	glfwWindowHint(GLFW_STENCIL_BITS, 0);
	//glfwWindowHint(GLFW_ALPHA_BITS, 0);
	glfwWindowHint(GLFW_DEPTH_BITS, 0);

	window = glfwCreateWindow(kWidth, kHeight, "Simple example", NULL, NULL);
	if (!window) {
		glfwTerminate();
		exit(EXIT_FAILURE);
	}
	glfwMakeContextCurrent(window);
	//(uncomment to enable correct color spaces) glEnable(GL_FRAMEBUFFER_SRGB);

	init_skia(kWidth, kHeight);

	glfwSwapInterval(1);
	glfwSetKeyCallback(window, key_callback);

	// Draw to the surface via its SkCanvas.
	SkCanvas* canvas = sSurface->getCanvas(); // We don't manage this pointer's lifetime.

	while (!glfwWindowShouldClose(window)) {
		glfwWaitEvents();
		SkPaint paint;
		paint.setColor(SK_ColorWHITE);
		canvas->drawPaint(paint);
		paint.setColor(SK_ColorBLUE);
		canvas->drawRect({100, 200, 300, 500}, paint);
		sContext->flush();

		glfwSwapBuffers(window);
	}

	cleanup_skia();

	glfwDestroyWindow(window);
	glfwTerminate();
	exit(EXIT_SUCCESS);
}
	/* Note: this Google copyright notice only applies to the original file, which has large sections copy-pasted here. my changes are under CC0 (public domain).

	* Copyright 2015 Google Inc.
	*
	* Use of this source code is governed by a BSD-style license that can be
	* found in the LICENSE file.
	*/

	/*
	The official instructions don't work well. These alternative instructions are intended to be the shortest path to get a minimal setup running.
	The Linux steps were run through successfully on Sept 2023.
	The Windows steps are known to be broken; the broken part is Step 7. The Include and Library directories should be tweaked.

	This was made by copy-pasting and fixing two sources: https://github.com/google/skia/tree/master/experimental/GLFWTest and https://gist.github.com/zester/5163313
	Don't bother trying these two sources; neither of them works.


	step 1: install glfw (on Linux, "sudo apt install libglfw3-dev" will get you an acceptable (and outdated) version. on Visual Studio, you can get glfw from vcpkg.)
	step 2: follow https://skia.org/docs/user/download/ to download and build skia.
	Move forward to either Windows step 6 or Linux step 6.

	Windows step 6, Visual Studio 2017:
	if you're in Windows, you will need to use bash (tested as of 2017; haven't tried recently). on my system, a copy of bash came with my installation of Git for Windows.
	cmd.exe doesn't allow single quotes, which are necessary to give the VC path. the various skia_use_foo commands are necessary to stop VS from erroring out when the headers are missing
	run these two commands, replacing "C:\Program Files (x86)\Microsoft Visual Studio\2017\Community\VC" with your own VC directory:
	gn gen out/Static --args='is_official_build=true win_vc="C:\Program Files (x86)\Microsoft Visual Studio\2017\Community\VC" skia_use_libpng=false skia_use_zlib=false skia_use_libwebp=false skia_enable_pdf=false skia_use_libjpeg_turbo=false skia_use_expat=false'
	ninja -C out/Static

	Windows step 7. Warning, this is outdated. The massive "FOLDER1\x" was changed to not be necessary, but I haven't tested the correct steps now:
	add this file to a new VS project
	append "FOLDER1\skia\include\core;FOLDER1\skia\include\gpu;FOLDER1\skia\include\config;FOLDER1\skia\include\utils;FOLDER2\glfw\include'" to the VC include directories of your project, where FOLDERX represents the directories you put them in.
	you must include all 4 skia folders because the files inside skia folders assume they see the other folders.
	if you're unfamiliar with how the include directory works, it's in Project->Properties, VC++ Directories, Include Directories.
	append "FOLDER1\skia\out\Static;FOLDER2\glfw\src\Debug;" to Library Directories, again replacing FOLDERX with the true location. add "opengl32.lib;skia.lib;glfw3.lib;" to Linker->Input->Additional Dependencies
	Set build mode to x64.
	Build! This will produce a debug mode binary.
	If in the future you want a release mode binary, you will need to re-build glfw in release mode, and change the glfw library folder to FOLDER2\glfw\src\Release;

	Linux step 6, Ubuntu 23.04. Sept 3, 2023:
	Run:
	sudo apt install clang libjpeg-dev libicu-dev libwebp-dev libfontconfig-dev
	bin/gn gen out/Static --args='is_official_build=true cc="clang" cxx="clang++"'
	ninja -C out/Static

	Linux step 7:
	download this file as "glfw_ship.cpp", and place it in the parent folder of the "skia" directory. (this just makes "-Iskia" in the right place)
	g++ -g -std=c++1z glfw_ship.cpp -lskia -ldl -lpthread -ljpeg -lfreetype -lz -lpng -lglfw -lfontconfig -lwebp -lwebpmux -lwebpdemux -lGL -Iskia -Lskia/out/Static/
	./a.out


	eventually, you will want color-correct spaces, and there are 5 places below (Ctrl+F "enable correct color spaces"), where you should replace/uncomment lines to enable this.
	warning: color-correct spaces don't work in VMWare, because mesa doesn't support it.
	*/

	#include "GLFW/glfw3.h"
	#define SK_GANESH
	#define SK_GL
	#include "include/gpu/GrBackendSurface.h"
	#include "include/gpu/GrDirectContext.h"
	#include "include/gpu/gl/GrGLInterface.h"
	#include "include/gpu/gl/GrGLAssembleInterface.h"
	#include "include/gpu/ganesh/SkSurfaceGanesh.h"
	#include "include/gpu/ganesh/gl/GrGLBackendSurface.h"
	#include "include/core/SkCanvas.h"
	#include "include/core/SkColorSpace.h"
	#include "include/core/SkSurface.h"

	#include <stdio.h>
	#include <stdlib.h>

	//uncomment the two lines below to enable correct color spaces
	//#define GL_FRAMEBUFFER_SRGB 0x8DB9
	//#define GL_SRGB8_ALPHA8 0x8C43

	GrDirectContext* sContext = nullptr;
	SkSurface* sSurface = nullptr;

	void error_callback(int error, const char* description) {
	fputs(description, stderr);
	}

	void key_callback(GLFWwindow* window, int key, int scancode, int action, int mods) {
	if (key == GLFW_KEY_ESCAPE && action == GLFW_PRESS)
	glfwSetWindowShouldClose(window, GL_TRUE);
	}

	void init_skia(int w, int h) {
	auto interface = GrGLMakeNativeInterface();
	if (interface == nullptr) {
	//backup plan. see https://gist.github.com/ad8e/dd150b775ae6aa4d5cf1a092e4713add?permalink_comment_id=4680136#gistcomment-4680136
	interface = GrGLMakeAssembledInterface(
	nullptr, (GrGLGetProc) * [](void, const char p) -> void* { return (void*)glfwGetProcAddress(p); });
	}
	sContext = GrDirectContext::MakeGL(interface).release();

	GrGLFramebufferInfo framebufferInfo;
	framebufferInfo.fFBOID = 0; // assume default framebuffer
	// We are always using OpenGL and we use RGBA8 internal format for both RGBA and BGRA configs in OpenGL.
	//(replace line below with this one to enable correct color spaces) framebufferInfo.fFormat = GL_SRGB8_ALPHA8;
	framebufferInfo.fFormat = GL_RGBA8;

	SkColorType colorType = kRGBA_8888_SkColorType;
	GrBackendRenderTarget backendRenderTarget = GrBackendRenderTargets::MakeGL(w, h,
	0, // sample count
	0, // stencil bits
	framebufferInfo);

	//(replace line below with this one to enable correct color spaces) sSurface = SkSurfaces::WrapBackendRenderTarget(sContext, backendRenderTarget, kBottomLeft_GrSurfaceOrigin, colorType, SkColorSpace::MakeSRGB(), nullptr).release();
	sSurface = SkSurfaces::WrapBackendRenderTarget(sContext, backendRenderTarget, kBottomLeft_GrSurfaceOrigin, colorType, nullptr, nullptr).release();
	if (sSurface == nullptr) abort();
	}

	void cleanup_skia() {
	delete sSurface;
	delete sContext;
	}

	const int kWidth = 960;
	const int kHeight = 640;

	int main(void) {
	GLFWwindow* window;
	glfwSetErrorCallback(error_callback);
	if (!glfwInit()) {
	exit(EXIT_FAILURE);
	}

	glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
	glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 2);
	glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE);
	glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
	//(uncomment to enable correct color spaces) glfwWindowHint(GLFW_SRGB_CAPABLE, GL_TRUE);
	glfwWindowHint(GLFW_STENCIL_BITS, 0);
	//glfwWindowHint(GLFW_ALPHA_BITS, 0);
	glfwWindowHint(GLFW_DEPTH_BITS, 0);

	window = glfwCreateWindow(kWidth, kHeight, "Simple example", NULL, NULL);
	if (!window) {
	glfwTerminate();
	exit(EXIT_FAILURE);
	}
	glfwMakeContextCurrent(window);
	//(uncomment to enable correct color spaces) glEnable(GL_FRAMEBUFFER_SRGB);

	init_skia(kWidth, kHeight);

	glfwSwapInterval(1);
	glfwSetKeyCallback(window, key_callback);

	// Draw to the surface via its SkCanvas.
	SkCanvas* canvas = sSurface->getCanvas(); // We don't manage this pointer's lifetime.

	while (!glfwWindowShouldClose(window)) {
	glfwWaitEvents();
	SkPaint paint;
	paint.setColor(SK_ColorWHITE);
	canvas->drawPaint(paint);
	paint.setColor(SK_ColorBLUE);
	canvas->drawRect({100, 200, 300, 500}, paint);
	sContext->flush();

	glfwSwapBuffers(window);
	}

	cleanup_skia();

	glfwDestroyWindow(window);
	glfwTerminate();
	exit(EXIT_SUCCESS);
	}