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我对 GTK 有点陌生，对开罗也很陌生。我的任务是创建一个应用程序，该应用程序需要将 PNG 作为背景并将包含字母和数字的多个 PNG 文件合成到背景 PNG 上，以便最终得到一个可以转换、旋转、缩放的 PNG等等。我可能觉得有用的任何提示、教程、代码示例？与 GTK 的情况一样，Cairo 文档对于尝试做比绘制形状更复杂的事情的初学者来说似乎有些欠缺。

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2 回答 2

9

看看这个简单的例子。它仅使用 cairo：

#include <cairo.h>

int main()
{
    //Load a few images from files
    cairo_surface_t *surf1 = cairo_image_surface_create_from_png("a.png");
    cairo_surface_t *surf2 = cairo_image_surface_create_from_png("b.png");

    //Create the background image
    cairo_surface_t *img = cairo_image_surface_create(CAIRO_FORMAT_ARGB32, 100, 100);

    //Create the cairo context
    cairo_t *cr = cairo_create(img);

    //Initialize the image to black transparent
    cairo_set_source_rgba(cr, 0,0,0, 1);
    cairo_paint(cr);

    //Paint one image
    cairo_set_source_surface(cr, surf1, 0, 0);
    cairo_paint(cr);

    //Paint the other image
    cairo_set_source_surface(cr, surf2, 50, 50);
    cairo_paint(cr);

    //Destroy the cairo context and/or flush the destination image
    cairo_surface_flush(img);
    cairo_destroy(cr);

    //And write the results into a new file
    cairo_surface_write_to_png(img, "result.png");

    //Be tidy and collect your trash
    cairo_surface_destroy(img);
    cairo_surface_destroy(surf1);
    cairo_surface_destroy(surf2);

    return 0;

}
于 2012-06-13T17:03:07.990 回答
4

谢谢罗德里戈，这是一个很好的例子！

对于所有C# 程序员，这里是翻译成 C# 的完全相同的示例。我在 SetSourceRGBA() 中只做了一个小改动——允许使用透明背景图像而不是黑色：

Using Cairo;

    //Load a few images from files
    ImageSurface surf1 = new ImageSurface("a.png");
    ImageSurface surf2 = new ImageSurface("b.png");

    //Create the background image
    ImageSurface img = new ImageSurface(Format.Argb32, 200, 200);

    //Create the cairo context
    Context cr = new Context(img);

    //Initialize the image to black transparent
    // cr.SetSourceRGBA(255,255,255,1); // This will create the background image with white background
    // cr.SetSourceRGBA(0,0,0,1);       // This will create the background image with black background
    cr.SetSourceRGBA(0,0,0,0);          // This creates the background image with transparent background
    cr.Paint ();


    //Paint one image
    cr.SetSourceSurface(surf1,0,0);
    cr.Paint();

    //Paint the other image
    cr.SetSourceSurface(surf2, 25, 50);
    cr.Paint();

    //Destroy the cairo context and/or flush the destination image
    img.Flush();

    //And write the results into a new file
    img.WriteToPng("result.png");

    //Be tidy and collect your trash
    img.Dispose();
    img.Destroy();
    surf1.Destroy ();
    surf2.Destroy();
于 2012-08-30T21:00:30.313 回答