translate


Description:

public void translate (double tx, double ty)

Example: Cartesian coordinate system (I):

public static int main (string[] args) {
// Create a context:
Cairo.ImageSurface surface = new Cairo.ImageSurface (Cairo.Format.ARGB32, 500, 500);
Cairo.Context context = new Cairo.Context (surface);

// Transformations:
context.translate (250, 250);
context.scale (1, -1);

// Y-Axis:
context.move_to (-250, 0);
context.line_to (250, 0);
context.stroke ();

// X-Axis:
context.move_to (0, -250);
context.line_to (0, 250);
context.stroke ();

// P (20, 10)
context.set_source_rgba (0, 0, 0, 1);
context.arc (20, 10, 2, 0, 2*Math.PI);
context.fill ();

// Save the image:
surface.write_to_png ("img.png");

return 0;
}

valac --pkg cairo cartesian-coordinate-system.vala

Example: Fill rules:

public static int main (string[] args) {
// Create a context:
Cairo.ImageSurface surface = new Cairo.ImageSurface (Cairo.Format.ARGB32, 256, 256);
Cairo.Context context = new Cairo.Context (surface);

context.set_line_width (6);

// First part:
context.rectangle (12, 12, 232, 70);
context.new_sub_path ();
context.arc (64, 64, 40, 0, 2*Math.PI);
context.new_sub_path ();
context.arc_negative (192, 64, 40, 0, -2*Math.PI);

context.set_fill_rule (Cairo.FillRule.EVEN_ODD);
context.set_source_rgb (0, 0.7, 0);
context.fill_preserve ();
context.set_source_rgb (0, 0, 0);
context.stroke ();

// Second part:
context.translate (0, 128);
context.rectangle (12, 12, 232, 70);
context.new_sub_path ();
context.arc (64, 64, 40, 0, 2*Math.PI);
context.new_sub_path ();
context.arc_negative (192, 64, 40, 0, -2*Math.PI);

context.set_fill_rule (Cairo.FillRule.WINDING);
context.set_source_rgb (0, 0, 0.9);
context.fill_preserve ();
context.set_source_rgb (0, 0, 0);
context.stroke ();

// Save the image:
surface.write_to_png ("img.png");

return 0;
}

valac --pkg cairo fill-rule.vala



2022 vala-language.org