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97 lines
3.9 KiB
97 lines
3.9 KiB
SkQP Render Test Algorithm
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==========================
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The following is a description of the render test validation algorithm that
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will be used by the version of SkQP that will be released for Android Q-release.
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There is a global macro constant: `SK_SKQP_GLOBAL_ERROR_TOLERANCE`, which
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reflects the `gn` variable `skia_skqp_global_error_tolerance`. This is usually
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set to 8.
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First, look for a file named `skqp/rendertests.txt` in the
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`platform_tools/android/apps/skqp/src/main/assets` directory. The format of
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this file is: each line contains one render test name, followed by a comma,
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followed by an integer. The integer is the `passing_threshold` for that test.
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For each test, we have a `max_image` and a `min_image`. These are PNG-encoded
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images stored in SkQP's APK's asset directory (in the paths `gmkb/${TEST}/min.png`
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and `gmkb/${TEST}/max.png`).
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The test input is a rendered image. This will be produced by running one of
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the render tests against the either the `vk` (Vulkan) or `gles` (OpenGL ES)
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Skia backend.
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Here is psuedocode for the error calculation:
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function calculate_pixel_error(pixel_value, pixel_max, pixel_min):
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pixel_error = 0
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for color_channel in { red, green, blue, alpha }:
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value = get_color(pixel_value, color_channel)
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v_max = get_color(pixel_max, color_channel)
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v_min = get_color(pixel_min, color_channel)
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if value > v_max:
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channel_error = value - v_max
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elif value < v_min:
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channel_error = v_min - value
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else:
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channel_error = 0
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pixel_error = max(pixel_error, channel_error)
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return max(0, pixel_error - SK_SKQP_GLOBAL_ERROR_TOLERANCE);
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function get_error(rendered_image, max_image, min_image):
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assert(dimensions(rendered_image) == dimensions(max_image))
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assert(dimensions(rendered_image) == dimensions(min_image))
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max_error = 0
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bad_pixels = 0
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total_error = 0
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error_image = allocate_bitmap(dimensions(rendered_image))
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for xy in list_all_pixel_coordinates(rendered_image):
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pixel_error = calculate_pixel_error(rendered_image(xy),
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max_image(xy),
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min_image(xy))
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if pixel_error > 0:
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for neighboring_xy in find_neighbors(xy):
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if not inside(neighboring_xy, dimensions(rendered_image)):
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continue
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pixel_error = min(pixel_error,
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calculate_pixel_error(rendered_image(xy),
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max_image(neighboring_xy),
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min_image(neighboring_xy)))
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if pixel_error > 0:
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max_error = max(max_error, pixel_error)
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bad_pixels += 1
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total_error += pixel_error
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error_image(xy) = linear_interpolation(black, red, pixel_error)
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else:
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error_image(xy) = white
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return ((total_error, max_error, bad_pixels), error_image)
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For each render test, there is a threshold value for `total_error`, :
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`passing_threshold`.
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If `passing_threshold >= 0 && total_error > passing_threshold`, then the test
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is a failure and is included in the report. if `passing_threshold == -1`, then
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the test always passes, but we do execute the test to verify that the driver
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does not crash.
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We generate a report with the following information for each test:
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backend_name,render_test_name,max_error,bad_pixels,total_error
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in CSV format in the file `out.csv`. A HTML report of just the failing tests
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is written to the file `report.html`. This version includes four images for
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each test: `rendered_image`, `max_image`, `min_image`, and `error_image`, as
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well as the three metrics: `max_error`, `bad_pixels`, and `total_error`.
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