45 lines
1.2 KiB
Dart
45 lines
1.2 KiB
Dart
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import 'dart:math' as math;
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import 'dart:ui';
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/// Circular capture guide (coin frame).
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class GuideFrame {
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static const double maxDiameterFraction = 0.72;
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static const double centerYFraction = 0.46;
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static Rect inViewport(Size size) {
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final d = math.min(size.width, size.height) * maxDiameterFraction;
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return Rect.fromCenter(
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center: Offset(size.width / 2, size.height * centerYFraction),
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width: d,
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height: d,
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);
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}
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static Rect inCoverImage({
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required Size viewport,
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required Size imageSize,
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}) {
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final guide = inViewport(viewport);
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final scale = math.max(
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viewport.width / imageSize.width,
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viewport.height / imageSize.height,
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);
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final dispW = imageSize.width * scale;
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final dispH = imageSize.height * scale;
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final ox = (viewport.width - dispW) / 2;
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final oy = (viewport.height - dispH) / 2;
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final mapped = Rect.fromLTRB(
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(guide.left - ox) / scale,
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(guide.top - oy) / scale,
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(guide.right - ox) / scale,
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(guide.bottom - oy) / scale,
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);
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return mapped.intersect(
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Rect.fromLTWH(0, 0, imageSize.width, imageSize.height),
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);
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}
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static Rect inImage(Size imageSize) => inViewport(imageSize);
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}
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