Class: QgsRenderChecker

class qgis.core.QgsRenderChecker

Bases: sip.wrapper

This is a helper class for unit tests that need to write an image and compare it to an expected result or render time.

QgsRenderChecker() Constructor for QgsRenderChecker.

QgsRenderChecker(QgsRenderChecker)

Methods

compareImages

Test using two arbitrary images (map renderer will not be used)

controlImagePath

Returns the base path containing the reference images.

dartMeasurements

Gets access to buffered dash messages.

drawBackground

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

elapsedTime

Returns the total elapsed time for the rendering test.

enableDashBuffering

Call this to enable internal buffering of dash messages.

expectedImageFile

Returns the path to the expected image file

imageToHash

Gets an md5 hash that uniquely identifies an image

isKnownAnomaly

Gets a list of all the anomalies.

matchPercent

Returns the percent of pixels which matched the control image.

matchTarget

Returns the total number of pixels in the control image.

mismatchCount

Returns the number of pixels which did not match the control image.

renderedImage

Returns the path of the rendered image generated by the test.

report

Returns the HTML report describing the results of the test run.

runTest

Test using renderer to generate the image to be compared.

setColorTolerance

Set tolerance for color components used by runTest() and compareImages().

setControlExtension

Sets file extension for the control image.

setControlImagePath

Sets the base path containing the reference images.

setControlName

Sets the base directory name for the control image (with control image path suffixed).

setControlPathPrefix

Sets the path prefix where the control images are kept.

setControlPathSuffix

param name

setElapsedTimeTarget

param target

setMapSettings

New in version 2.4.

setRenderedImage

Sets the file name of the rendered image generated by the test.

setSizeTolerance

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

compareImages(self, testName: str, mismatchCount: int = 0, renderedImageFile: str = '')bool

Test using two arbitrary images (map renderer will not be used)

Parameters
  • testName (str) –

    • to be used as the basis for writing a file to

    e.g. /tmp/theTestName.png

  • mismatchCount (int = 0) –

    • 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.

  • renderedImageFile (str = '') – to optionally override the output filename

note: make sure to call setExpectedImage and setRenderedImage first.

compareImages(self, testName: str, referenceImageFile: str, renderedImageFile: str, mismatchCount: int = 0) -> bool Test using two arbitrary images at the specified paths for equality.

New in version 3.18.

Return type

bool

controlImagePath(self)str

Returns the base path containing the reference images.

This defaults to an internal QGIS test data path, but can be changed via setControlImagePath().

Return type

str

dartMeasurements(self)List[QgsDartMeasurement]

Gets access to buffered dash messages. Only will return something if you call enableDashBuffering( True ); before.

Return type

List[QgsDartMeasurement]

Returns

buffered dash messages

drawBackground(image: QImage)

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

Parameters

image (QImage) –

elapsedTime(self)int

Returns the total elapsed time for the rendering test.

Note

this only records time for actual render part.

Return type

int

enableDashBuffering(self, enable: bool)

Call this to enable internal buffering of dash messages. You may later call dashMessages() to get access to the buffered messages. If disabled (default) dash messages will be sent immediately.

Parameters

enable (bool) – Enable or disable buffering

expectedImageFile(self)str

Returns the path to the expected image file

Return type

str

Returns

Path to the expected image file

imageToHash(self, imageFile: str)str

Gets an md5 hash that uniquely identifies an image

Parameters

imageFile (str) –

Return type

str

isKnownAnomaly(self, diffImageFile: str)bool

Gets a list of all the anomalies. An anomaly is a rendered difference file where there is some red pixel content (indicating a render check mismatch), but where the output was still acceptable. If the render diff matches one of these anomalies we will still consider it to be acceptable.

Return type

bool

Returns

a bool indicating if the diff matched one of the anomaly files

Parameters

diffImageFile (str) –

matchPercent(self)float

Returns the percent of pixels which matched the control image.

Return type

float

matchTarget(self)int

Returns the total number of pixels in the control image.

Return type

int

mismatchCount(self)int

Returns the number of pixels which did not match the control image.

Return type

int

renderedImage(self)str

Returns the path of the rendered image generated by the test.

This method will return either the path set with setRenderedImage() or generated in runTest().

Return type

str

report(self)str

Returns the HTML report describing the results of the test run.

Return type

str

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

Test using renderer to generate the image to be compared.

Parameters
  • testName (str) –

    • to be used as the basis for writing a file to

    e.g. /tmp/theTestName.png

  • mismatchCount (int = 0) –

    • 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 setMapRenderer first

Return type

bool

setColorTolerance(self, colorTolerance: int)

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

Parameters

colorTolerance (int) – is maximum difference for each color component including alpha to be considered correct.

New in version 2.1.

setControlExtension(self, extension: str)

Sets file extension for the control image. By default it is “png”

New in version 3.20.

Parameters

extension (str) –

setControlImagePath(self, path: str)

Sets the base path containing the reference images.

New in version 3.18.

Parameters

path (str) –

setControlName(self, name: str)

Sets the base directory name for the control image (with control image path suffixed).

The path to the image will be constructed like this: controlImagePath() + ‘/’ + control name + ‘/’ + control name + ‘.’ + extension (‘png’ by default)

Parameters

name (str) –

setControlPathPrefix(self, name: str)

Sets the path prefix where the control images are kept. This will be appended to controlImagePath().

Parameters

name (str) –

setControlPathSuffix(self, name: str)
Parameters

name (str) –

setElapsedTimeTarget(self, target: int)
Parameters

target (int) –

setMapSettings(self, mapSettings: QgsMapSettings)

New in version 2.4.

Parameters

mapSettings (QgsMapSettings) –

setRenderedImage(self, imageFileName: str)

Sets the file name of the rendered image generated by the test.

Parameters

imageFileName (str) –

setSizeTolerance(self, xTolerance: int, yTolerance: int)

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

Parameters
  • xTolerance (int) – x tolerance in pixels

  • yTolerance (int) – y tolerance in pixels

New in version 2.12.