Class: QgsMultiRenderChecker

class qgis.core.QgsMultiRenderChecker

Bases: sip.wrapper

Constructor for QgsMultiRenderChecker.

QgsMultiRenderChecker(QgsMultiRenderChecker)

This class allows checking rendered images against comparison images. Its main purpose is for the unit testing framework.

It will either <ul> <li>take an externally rendered image (setRenderedImage())</li> <li>render the image based on provided mapSettings (setMapSettings())</li> </ul>

This image will then be compared against one or several images in a folder inside the control directory (tests/testdata/control_images/{controlName}).

There are modes for single and for multiple reference images. <ul> <li>If there are no subfolders in the control directory, it will assume an image with the name {controlImage}.png in the control directory itself.</li>

<li>If there are subfolders inside the control directory, it will search for images with the name {controlImage}.png in every subfolder.</li> </ul>

For every control image there may be one or several randomly named anomaly images defining allowed anomalies. For every control image, the allowed mismatch and color tolerance values will be calculated individually.

New in version 2.8: Methods

controlImagePath Returns the path to the control images.
drawBackground Draws a checkboard pattern for image backgrounds, so that opacity is visible without requiring a transparent background for the image
report Returns a report for this test
runTest Test using renderer to generate the image to be compared.
setColorTolerance Set tolerance for color components used by runTest() Default value is 0.
setControlName Base directory name for the control image (with control image path suffixed) the path to the image will be constructed like this: controlImagePath + ‘/’ + mControlName + ‘/’ + mControlName + ‘.png’
setControlPathPrefix
setMapSettings Set the map settings to use to render the image
setRenderedImage Set the path to the rendered image.
setSizeTolerance Sets the largest allowable difference in size between the rendered and the expected image.

Signals

Attributes

controlImagePath(self) → str

Returns the path to the control images.

drawBackground(image: QImage)

Draws a checkboard pattern for image backgrounds, so that opacity is visible without requiring a transparent background for the image

report(self) → str

Returns a report for this test

runTest(self, testName: str, mismatchCount: int = 0) → bool

Test using renderer to generate the image to be compared.

Parameters:
  • testName
    • to be used as the basis for writing a file to

    e.g. /tmp/theTestName.png

  • mismatchCount
    • defaults to 0 - the number of pixels that

    are allowed to be different from the control image. In some cases rendering may be non-deterministic. This parameter allows you to account for that by providing a tolerance.

Note

make sure to call setExpectedImage and setMapSettings first

setColorTolerance(self, colorTolerance: int)

Set tolerance for color components used by runTest() Default value is 0.

Parameters:colorTolerance – The maximum difference for each color component including alpha to be considered correct.
setControlName(self, name: str)

Base directory name for the control image (with control image path suffixed) the path to the image will be constructed like this: controlImagePath + ‘/’ + mControlName + ‘/’ + mControlName + ‘.png’

setControlPathPrefix(self, prefix: str)
setMapSettings(self, mapSettings: QgsMapSettings)

Set the map settings to use to render the image

Parameters:mapSettings – The map settings
setRenderedImage(self, renderedImagePath: str)

Set the path to the rendered image. If this is not set or set to null QString, an image will be rendered based on the provided mapsettings

Parameters:renderedImagePath – A path to the rendered image with which control images will be compared
setSizeTolerance(self, xTolerance: int, yTolerance: int)

Sets the largest allowable difference in size between the rendered and the expected image.

Parameters:
  • xTolerance – x tolerance in pixels
  • yTolerance – y tolerance in pixels

New in version 3.0.