2D drawing canvas

[porfirio]

Hi.

I'm new to this forum and to SFML.

I would like to know if there is any 2d rendering API like Html5 CanvasRenderingContext2D or Flash Graphics

Something like:

Canvas canvas;
canvas.fillRect(10, 10, 55, 50); 
canvas.drawCircle(10, 10, 20);

And then draw it to window:

window.draw(canvas);

Would make it allot easier to draw some primitives and paths instehead of creating multiple objects and drawing them to window.

Is there anything like that?

[Laurent]

No. But SFML has classes for drawing shapes, so if your requirements are not too high it could be enough.

[porfirio]

No. But SFML has classes for drawing shapes, so if your requirements are not too high it could be enough.

Yeah, for basic shapes it is enough. But a good path api with lineTo, acrTo, quadraticCurveTo, etc... would be nice, but hard to implement i imagine.

[Nexus]

For other geometries, you can have a look at Zoost and Zoom.

[Groogy]

I think someone made a SVG add on to SFML at some point, what happend to that project? Because that would be perfect for drawing paths.

Anyway you could implement your own Canvas/Path interface if you want and use sf::VertexArray in the background.

Even if SFML maybe not have exactly what you need it provides the tools you need in order to do it yourself

[porfirio]

I think someone made a SVG add on to SFML at some point, what happend to that project? Because that would be perfect for drawing paths.

Anyway you could implement your own Canvas/Path interface if you want and use sf::VertexArray in the background.

Even if SFML maybe not have exactly what you need it provides the tools you need in order to do it yourself

Thank you all.

SFML seems to be nice and powerfull, and the community verry friendly
I've looked at other libs like SDL and Allegro but SFML is C++ and seems easier to bootstrap.

[caracal]

You can use Googles Skia Library

Note: Might not work out of the box

#include <SFML/Graphics.hpp>
#include "SkCanvas.h"
#include "SkGraphics.h"
#include "SkImageEncoder.h"
#include "SkString.h"
#include "SkTemplates.h"
#include "SkTypeface.h"
 
#include <iostream>
 
// g++ main.cpp -Wl,-rpath,./ -L. -lskia -Iinclude/core -Iinclude/config -Iinclude/images -lpthread -lfreetype -lpng -lsfml-window -lsfml-graphics -lsfml-system
 
using namespace std;
 
int main(int argc, char **argv) {
 
  int width = 800;
  int height = 600;
 
  // Create the main window
  sf::RenderWindow window(sf::VideoMode(width, height), "SFML window");
  sf::Image image;
 
 
 
    SkAutoGraphics ag;
 
    //Set Text To Draw
    SkString text("Hydra Skia v0.0.1a");
 
    SkPaint paint;
 
    //Set Text ARGB Color
    paint.setARGB(255, 255, 255, 255);
 
    //Turn AntiAliasing On
    paint.setAntiAlias(true);
    paint.setLCDRenderText(true);
    paint.setTypeface(SkTypeface::CreateFromName("sans-serif", SkTypeface::kNormal));
 
    //Set Text Size
    paint.setTextSize(SkIntToScalar(20));
 
    SkBitmap bitmap;
    bitmap.setConfig(SkBitmap::kARGB_8888_Config, width / 2, height);
    bitmap.allocPixels();
 
    //Create Canvas
    SkCanvas canvas(bitmap);
    canvas.drawARGB(100, 25, 25, 25);
 
    //Text X, Y Position Varibles
    int x = 80;
    int y = 60;
 
    canvas.drawText(text.c_str(), text.size(), x, y, paint);
 
    //Set Style and Stroke Width
    paint.setStyle(SkPaint::kStroke_Style);
    paint.setStrokeWidth(3);
 
    //Draw A Rectangle
    SkRect rect;
    paint.setARGB(255, 0, 0, 0);
    //Left, Top, Right, Bottom
    rect.set(50, 100, 200, 200);
    canvas.drawRoundRect(rect, 20, 20, paint);
 
    canvas.drawOval(rect, paint);
 
    //Draw A Line
    canvas.drawLine(10, 300, 300, 300, paint);
 
    //Draw Circle (X, Y, Size, Paint)
    canvas.drawCircle(100, 400, 50, paint);
 
 
    image.Create(bitmap.width(), bitmap.height(), reinterpret_cast<const sf::Uint8*>(bitmap.getPixels()));
 
  // Load a sprite to display
  sf::Texture texture;
  if (!texture.LoadFromImage(image))
          return EXIT_FAILURE;
 
  sf::Sprite sprite(texture);
  //sprite.SetPosition(100, 100);
  //sprite.Resize(400, 400);
 
  // Load a sprite to display
  sf::Texture tex;
  if (!tex.LoadFromFile("background.jpg"))
         return EXIT_FAILURE;
  sf::Sprite texs(tex);
 
 
  // Start the game loop
  while (window.IsOpened())
  {
 
         // Process events
         sf::Event event;
         while (window.PollEvent(event))
         {
             // Close window : exit
             if (event.Type == sf::Event::Closed)
                 window.Close();
         }
 
         // Clear screen
         window.Clear();
 
         window.Draw(texs);
         window.Draw(sprite);
 
         // Update the window
         window.Display();
 
     }
 
 
 
     return EXIT_SUCCESS;
 }
 

The following code demonstrates Skia in a GL Context using GLFW. Note havent converted it to SFML2 yet.

#include <stdio.h>
#include <stdlib.h>
#include <Windows.h>
#include "glfw/glfw.h"
 
#include "skia/include/gpu/GrContext.h"
#include "skia/include/gpu/GrRenderTarget.h"
#include "skia/include/gpu/GrGLInterface.h"
#include "skia/include/gpu/SkGpuDevice.h"
#include "skia/include/gpu/SkGpuCanvas.h"
#include "skia/include/gpu/SkNativeGLContext.h"
#include "skia/include/core/SkCanvas.h"
#include "skia/include/core/SkGraphics.h"
 
int main( int ac,char** av )
{
    SkAutoGraphics ag;
    int window_width = 800,
         window_height = 600;
    //*
    if( glfwInit() == GL_FALSE )
    {
        printf( "Could not initialize GLFW. Aborting.\n" );
        exit( 0 );
    }
 
    // This function calls wglMakeCurrent somewhere in its execution, so make sure that (or its platform specific equivalent) it is called when porting to other frameworks.
    if (glfwOpenWindow(window_width, window_height, 8,8,8,8,24,8, GLFW_WINDOW) == GL_FALSE)
    {
        printf( "Could not open GLFW window. Aborting.\n" );
        exit( 0 );
    }
    // */
 
    const GrGLInterface* fGL = GrGLCreateNativeInterface();
    GrContext* fGrContext = GrContext::Create( kOpenGL_Shaders_GrEngine,(GrPlatform3DContext)fGL );
    if( fGrContext == 0x0 )
    {
        printf("\nfGrContext was null");
        exit( 0 );
    }
 
 
    GrRenderTarget* fGrRenderTarget;)
 
 
    GrPlatformRenderTargetDesc desc;)
    desc.fWidth = window_width;)
    desc.fHeight = window_height;)
    desc.fConfig = kSkia8888_PM_GrPixelConfig;)
    GR_GL_GetIntegerv(fGL, GR_GL_SAMPLES, &desc.fSampleCnt);)
    GR_GL_GetIntegerv(fGL, GR_GL_STENCIL_BITS, &desc.fStencilBits);)
    GrGLint buffer;)
    GR_GL_GetIntegerv(fGL, GR_GL_FRAMEBUFFER_BINDING, &buffer);)
    desc.fRenderTargetHandle = buffer;
 
    // I had some serious trouble with segmentation faults and failures arising from this function. Perhaps some more robust error checking is in order?
    fGrRenderTarget = fGrContext->createPlatformRenderTarget(desc);
 
    // Canvi (Canvasses?) only really care about the device they contain, so you can ignore the SkGpuCanvas.
    SkCanvas* gpuCanvas = new SkCanvas();
    gpuCanvas->setDevice(new SkGpuDevice(fGrContext,fGrRenderTarget))->unref();
 
    glfwSetWindowTitle( "Skia GLFW Test" );
 
    while( true )
    {
        // Draw a red background with a gray, semi-transparent circle in the top left corner.
        gpuCanvas->drawColor( SK_ColorRED );
        SkRect r(SkRect::MakeWH(200,200));
        SkPaint p;
        p.setARGB( 200,100,100,100 );
        gpuCanvas->drawOval( r,p );
 
        glfwSwapBuffers();
        fGrContext->flush(false);
        Sleep( 1 );
    }
    return 1;
}
 

Or you could use the Nvidia Path Rendering Ext and just feed it pure SVG or Postscript