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Make Canvas cullRect optional and make Rect.largest a static field. (flutter/engine#4551)

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Fixes https://github.com/flutter/flutter/issues/7201.

The change from `new Rect.largest()` to `Rect.largest` saves a few
allocations since we'll be using these with every Canvas.
This commit is contained in:
Ian Hickson
2018-01-16 10:08:08 -08:00
committed by GitHub
parent c03cd3798d
commit 08f3598be8
2 changed files with 13 additions and 14 deletions
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18
engine/src/flutter/lib/ui/geometry.dart
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@@ -625,16 +625,6 @@ class Rect {
..[3] = math.max(a.dy, b.dy);
}
/// Construct the largest finite rectangle.
Rect.largest() {
const double skScalarMax = 3.402823466e+38; // from Skia's SkScalar.h
_value
..[0] = -skScalarMax
..[1] = -skScalarMax
..[2] = skScalarMax
..[3] = skScalarMax;
}
static const int _kDataSize = 4;
final Float32List _value = new Float32List(_kDataSize);
@@ -663,6 +653,14 @@ class Rect {
/// A rectangle with left, top, right, and bottom edges all at zero.
static final Rect zero = new Rect._();
static const double _skScalarMax = 3.402823466e+38; // from Skia's SkScalar.h
/// A rectangle that covers the entire coordinate space.
///
/// This actually covers the space from about -3e38,-3e38 to about 3e38,3e38.
/// This is the space over which graphics operations are valid.
static final Rect largest = new Rect.fromLTRB(-_skScalarMax, -_skScalarMax, _skScalarMax, _skScalarMax);
/// Whether any of the coordinates of this rectangle are equal to positive infinity.
// included for consistency with Offset and Size
bool get isInfinite {

9
engine/src/flutter/lib/ui/painting.dart
View File

@@ -1771,18 +1771,19 @@ class Canvas extends NativeFieldWrapperClass2 {
/// given picture recorder.
///
/// Graphical operations that affect pixels entirely outside the given
/// cullRect might be discarded by the implementation. However, the
/// `cullRect` might be discarded by the implementation. However, the
/// implementation might draw outside these bounds if, for example, a command
/// draws partially inside and outside the `cullRect`. To ensure that pixels
/// outside a given region are discarded, consider using a [clipRect].
/// outside a given region are discarded, consider using a [clipRect]. The
/// `cullRect` is optional; by default, all operations are kept.
///
/// To end the recording, call [PictureRecorder.endRecording] on the
/// given recorder.
Canvas(PictureRecorder recorder, Rect cullRect) {
Canvas(PictureRecorder recorder, [ Rect cullRect ]) {
assert(recorder != null);
if (recorder.isRecording)
throw new ArgumentError('"recorder" must not already be associated with another Canvas.');
assert(cullRect != null);
cullRect ??= Rect.largest;
_constructor(recorder, cullRect.left, cullRect.top, cullRect.right, cullRect.bottom);
}
void _constructor(PictureRecorder recorder,