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ch...@google.com
Sergio shared a WIP CL to calculate more correct bounds. You can see in the screenshot attached here that it does a better job of tightening the bounds around the object (the yellow box), but that it misses some of the curves which expand beyond these tighter bounds. In particular, note the two triangles and the two blob shapes (rotated round rects).
I've attached another 2 screenshots from the ShapeEditor view of one of the blobs, showing the shape and controls/anchors. You can see that the tighter bounds (yellow rectangle) are constrained to the anchors, but the curves at the end go beyond those points and exceed the bounds.
I've attached another 2 screenshots from the ShapeEditor view of one of the blobs, showing the shape and controls/anchors. You can see that the tighter bounds (yellow rectangle) are constrained to the anchors, but the curves at the end go beyond those points and exceed the bounds.
ch...@google.com
Part of the problem is that the min/max values are assigned the anchors to begin with. That would cause the problem we're seeing in #2, because these new bounds are constrained to the rectangle created by the anchor points, even if the control points cause curves to go outside of those bounds.
But that's not all of the problem here. When I changed those min/max values to use the control points instead, the bounds expanded to be essentially the same as the estimated bounds from before. So there's more to it.
But that's not all of the problem here. When I changed those min/max values to use the control points instead, the bounds expanded to be essentially the same as the estimated bounds from before. So there's more to it.
ch...@google.com
Some of #3 is incorrect - the bounds can be expanded from the initial min/max values, so it is fine to have them start at the anchor points.
Meanwhile, I thought part of the problem might be calculating derivatives/etc for zero-length curves (of which there are many, given the way our shape rounding works). But adding in a check for this (setting the bounds of a curve to the same point when the anchors are equal within the distance epsilon) did not fix the problem; we still end up with bounds that are inside some of the curves (see attached screenshot)
Meanwhile, I thought part of the problem might be calculating derivatives/etc for zero-length curves (of which there are many, given the way our shape rounding works). But adding in a check for this (setting the bounds of a curve to the same point when the anchors are equal within the distance epsilon) did not fix the problem; we still end up with bounds that are inside some of the curves (see attached screenshot)
ap...@google.com
Project: platform/frameworks/support
Branch: androidx-main
commit 958577b15712233aa487003deb0ab37de3af7ab7
Author: Chet Haase <chet@google.com>
Date: Wed Dec 20 13:21:53 2023
Added more bounds calculation utilities
Previously, calculateBounds() returned the estimated bounds
for a RoundedPolygon. This is reasonable in most cases, but sometimes
you want the actual/minimal bounds instead. Also, sometimes you want
the max bounds for an object that might be rotated within its container,
so you need to size the container appropriately.
This CL introduces options for bounds calculations to handle these
new cases, along with some minor cleanups along the way.
Bug: 317286450
Test: Existing tests pass, added new bounds tests
Relnote: Now more options for retrieving exact and max bounds
Change-Id: I6d49f468a28c1f360000e8370f02a50841f744e4
M graphics/graphics-shapes/api/current.txt
M graphics/graphics-shapes/api/restricted_current.txt
M graphics/graphics-shapes/src/androidInstrumentedTest/kotlin/androidx/graphics/shapes/PolygonTest.kt
M graphics/graphics-shapes/src/commonMain/kotlin/androidx/graphics/shapes/Cubic.kt
M graphics/graphics-shapes/src/commonMain/kotlin/androidx/graphics/shapes/RoundedPolygon.kt
M graphics/graphics-shapes/src/commonMain/kotlin/androidx/graphics/shapes/Utils.kt
M graphics/integration-tests/testapp-compose/src/main/java/androidx/graphics/shapes/testcompose/DebugDraw.kt
M graphics/integration-tests/testapp-compose/src/main/java/androidx/graphics/shapes/testcompose/MainActivity.kt
https://android-review.googlesource.com/2889768
Branch: androidx-main
commit 958577b15712233aa487003deb0ab37de3af7ab7
Author: Chet Haase <chet@google.com>
Date: Wed Dec 20 13:21:53 2023
Added more bounds calculation utilities
Previously, calculateBounds() returned the estimated bounds
for a RoundedPolygon. This is reasonable in most cases, but sometimes
you want the actual/minimal bounds instead. Also, sometimes you want
the max bounds for an object that might be rotated within its container,
so you need to size the container appropriately.
This CL introduces options for bounds calculations to handle these
new cases, along with some minor cleanups along the way.
Bug: 317286450
Test: Existing tests pass, added new bounds tests
Relnote: Now more options for retrieving exact and max bounds
Change-Id: I6d49f468a28c1f360000e8370f02a50841f744e4
M graphics/graphics-shapes/api/current.txt
M graphics/graphics-shapes/api/restricted_current.txt
M graphics/graphics-shapes/src/androidInstrumentedTest/kotlin/androidx/graphics/shapes/PolygonTest.kt
M graphics/graphics-shapes/src/commonMain/kotlin/androidx/graphics/shapes/Cubic.kt
M graphics/graphics-shapes/src/commonMain/kotlin/androidx/graphics/shapes/RoundedPolygon.kt
M graphics/graphics-shapes/src/commonMain/kotlin/androidx/graphics/shapes/Utils.kt
M graphics/integration-tests/testapp-compose/src/main/java/androidx/graphics/shapes/testcompose/DebugDraw.kt
M graphics/integration-tests/testapp-compose/src/main/java/androidx/graphics/shapes/testcompose/MainActivity.kt
ch...@google.com
Problem fixed - we now offer the option to request actual bounds (or faster/approximated, based on a parameter to calculateBounds()).
We also offer a new API, calculateMaxBounds(), which returns the square bounds in which the object can be rotated without ever exceeding the bounds.
We also offer a new API, calculateMaxBounds(), which returns the square bounds in which the object can be rotated without ever exceeding the bounds.
Description
Meanwhile, the bounds are also limited to whatever the screen orientation of the shape is at the time. So if the caller was hoping to get the bounds once to calculate the size of the bounding view/composable and then rotate the shape within that area, they may find that the shape exceeds those bounds as it changes orientation. For a simple example, imagine a rectangle that is long in the x direction but short in the y direction, which would result in bounds that are similarly wide horizontally but short vertically, Rotating that rectangle would exceed the bounds in the Y direction quickly as the corners of the rectangle rotated outside of the original bounds.
It seems like we should provide more functionality for bounds calculations in two ways:
1) Exact bounds: Approximate bounds are sufficient for many purposes, and have the advantage of being cheap to compute (we are simply doing a bunch of float compares against all points in a shape). But if a caller wants the exact bounds for some reason, we should be able to calculate those by checking the bounds of the actual curves instead of just the points that created those curves. For example, in the attached screenshot of the clover, exact bounds would look closer to the yellow box than the green box, where the bounds met the outline of the clover's curves.
2) Max bounds: If a caller intends to rotate or otherwise change the orientation of a shape, we could calculate the max bounds. This is essentially the farthest point on any of the curves from the center, doubled, in both directions. For example, if the farthest point on a curve were (100, 100) away from the center, then the max bounds would be (-100, -100), (100, 100).
The caller can come up with these values already; they have access to the same underlying cubics that we would use to calculate these new bounds values. But it seems like the kind of utility that the library should provide directly to make it easier to position these shapes in a UI, where bounds help determine placement and sizing of the views/composables which contain these shapes.