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Hello there, recently I have been trying to experiment with vector graphics in C++. I want to make a Win32 app that reads an svg file and shows it on the screen. The program currently is simple. A window opens using the Win32 API and a .svg file is selected. This svg file's data is then converted to a struct data of my own. The conversion is good. The code of struct is as follows:

C++
#pragma once

#include <vector>
#include "Rect.h"

class VectorTexture
{
public:
	enum ShapeType
	{
		// Circle: x, y, r
		Circle,
		// Line: x1, y1, x2, y2, width
		Line,
		// Rectangle: x, y, width, height
		Rectangle,
		// Square: x, y, a
		Square,
		// Polygon: x[n], y[n]
		Polygon
	};

	struct Shape
	{
	public:
		ShapeType type;
		float data[];
	};

	Rect rect;
	std::vector<Shape> shapes;
};


Now, the next step is show the svg image. How can I rasterize the vector data that I have, to give me HBITMAP that I can show on the screen? If you know any resources, please put up a link.

Thanks in advance.

What I have tried:

I found a little about DDA and Bresenham algorithms but the only issue is that they are line-drawing algorithms and I am drawing shapes.
Posted
Updated 15-Nov-21 5:12am

You may want to look at Getting Started with Direct2D - Win32 apps | Microsoft Docs[^] Microsoft's latest graphics functions. Alternatively there are a number of third party libraries for handling SVG data, and Google will find them for you.
 
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The basic idea behind Bresenham and DDA can be applied to any polynomial function, not just lines (which are polynomials of first degree). The trick is to find a polynomial representation for a nonlinear curve.

Another important thing to consider when looking at bresenham ist that this algorithm represents a line in the form y=f(x), where f(x) is a simple polynomial of the form a*x+b. While there is no reason to do so in case of lines, a better approach is often the representation of a curve as a parametric function of both x and y: {x,y}=f(t). E. g. in case of a line, this function could be f(t)={t,a*t+b}.

In case of a circle with center {0,0} and radius r, you can define a polynomial like this: x*x+y*y-r*r=0. You can use DDA on this expression and find out whether increasing or decreasing x or y leads to a change of sign of this expression - if so, you've found coordinates on the raster image of the curve.


Of course, these kind of things have been implemented on graphic chips 30+ years ago ;-) , so unless you're producing (and hard-wiring) GPUs, there's no reason to do such things. Just use standard graphics functions such as those Richard pointed to in his solution.
 
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