PySide6.QtCanvasPainter.QCanvasCustomBrush

class QCanvasCustomBrush

QCanvasCustomBrush is a brush with custom shaders.

Details

QCanvasCustomBrush is a stroke/fill brush with custom vertex and/or fragment shaders.

These shaders are expected to be written in Vulkan-style GLSL, similarly to Qt Quick ShaderEffect shaders. They must always contain a QC_INCLUDE statement, either with "customfrag.glsl" or "customvert.glsl". This makes available a uniform block, the image and font textures, and a few helper functions.

Below is a simple example of a custom fragment shader:

#version 440

QC_INCLUDE "customfrag.glsl"

void main()
{
    float a = 0.6 + 0.2 * sin(0.1 * fragCoord.x + 4.0 * iTime);
    vec4 color = vec4(a, a, a, 1.0);
    fragColor = sdfFontAlpha() * globalAlpha * color;
    applyColorEffects(fragColor);
}

iTime is an example of a commonly used member in the built-in uniform block. Calling setTimeRunning() with true will make this value update automatically every frame, and can be used to drive animated content.

Shaders that are used with QCanvasCustomBrush must always be added to the application project via the qc_add_shaders() CMake function, provided by the Qt Canvas Painter package. This function performs additional preprocessing at build time before internally invoking the standard qt_add_shaders().

For example:

qc_add_shaders(app "app_custombrush_shaders"
    PREFIX
        "/shaders"
    FILES
        brush1.frag
)

At run time, the generated .qsb file can be used for example like this:

QCanvasCustomBrush customBrush(":/shaders/brush1.frag.qsb"));
customBrush.setTimeRunning(true); // iTime updates automatically
// expose custom data to the shader in data1
customBrush.setData1(QVector4D(1.0, 2.0, 3.0, 4.0));

The QCanvasCustomBrush can then be used in a fill, for example:

painter->setFillStyle(customBrush);

See also

Qt Canvas Painter - Gallery Example

Inheritance diagram of PySide6.QtCanvasPainter.QCanvasCustomBrush

Synopsis

Methods

Note

This documentation may contain snippets that were automatically translated from C++ to Python. We always welcome contributions to the snippet translation. If you see an issue with the translation, you can also let us know by creating a ticket on https:/bugreports.qt.io/projects/PYSIDE

__init__()

Constructs a default custom brush.

__init__(fragmentShader[, vertexShader={}])
Parameters:

  • fragmentShader – str

  • vertexShader – str

Constructs a custom brush.

The fragment shader is fragmentShader and the vertex shader is vertexShader. This constructor takes two filenames, where both files are expected to be .qsb files that are read and deserialized into QShader objects. The files can be a local file or embedded in the application via the The Qt Resource System.

When not specified, vertexShader defaults to an empty string, which implies that the default, standard shader is used for the vertex stage. It is also possible to pass an empty string as fragmentShader, and only provide a custom shader for vertexShader.

__ne__(rhs)
Parameters:

rhs – QCanvasCustomBrush

Return type:

bool

__eq__(rhs)
Parameters:

rhs – QCanvasCustomBrush

Return type:

bool

setData1(data)
Parameters:

data – QVector4D

Sets the uniform data1 value to data. This allows setting custom data into shaders.

setData2(data)
Parameters:

data – QVector4D

Sets the uniform data2 value to data. This allows setting custom data into shaders.

setData3(data)
Parameters:

data – QVector4D

Sets the uniform data3 value to data. This allows setting custom data into shaders.

setData4(data)
Parameters:

data – QVector4D

Sets the uniform data4 value to data. This allows setting custom data into shaders.

setFragmentShader(fragmentShader)
Parameters:

fragmentShader – QShader

Sets the custom brush to use fragmentShader.

setFragmentShader(fragmentShader)
Parameters:

fragmentShader – str

Sets the custom brush to use fragmentShader. This must be path to a valid qsb file. The file can be a local file or embedded in the application via the The Qt Resource System.

setTimeRunning(running)
Parameters:

running – bool

Sets the time running state to running. When this is true, the shader uniform iTime is updated automatically, and can be used to get the current animation running time in the shader.

The default value is false.

See also

timeRunning()

setVertexShader(vertexShader)
Parameters:

vertexShader – QShader

Sets the custom brush to use vertexShader.

setVertexShader(vertexShader)
Parameters:

vertexShader – str

Sets the custom brush to use vertexShader. This must be path to a valid qsb file. The file can be a local file or embedded in the application via the The Qt Resource System.

timeRunning()
Return type:

bool

Returns true if the time is running.

See also

setTimeRunning()