37 lines
1.6 KiB
Dart
37 lines
1.6 KiB
Dart
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// lib/editor/pdf/slide_export.dart
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//
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// Pure geometry for exporting pen-first slide annotations to PDF. Because the
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// pen canvas captures strokes NORMALIZED to the page rect ([0,1]), the export
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// just maps each normalized point into the slide image's draw rectangle on the
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// PDF page — no live-widget-size guessing, which is what made the old PPT
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// exporter misalign ink (see the removed ppt_annotator_screen comment).
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import 'dart:ui' show Offset, Rect, Size;
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/// The rectangle a slide [image] occupies when drawn "contain"-fit and centered
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/// on a PDF page of size [page]. Mirrors the live canvas's fit-to-view so the
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/// exported ink lands exactly where it was drawn.
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Rect slideDrawRect(Size page, Size image) {
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final iw = image.width <= 0 ? 1.0 : image.width;
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final ih = image.height <= 0 ? 1.0 : image.height;
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final scale = (page.width / iw) < (page.height / ih)
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? page.width / iw
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: page.height / ih;
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final drawW = iw * scale;
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final drawH = ih * scale;
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final offX = (page.width - drawW) / 2;
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final offY = (page.height - drawH) / 2;
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return Rect.fromLTWH(offX, offY, drawW, drawH);
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}
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/// Map a normalized stroke point ([0,1] of the page rect) to an absolute point
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/// inside the slide's [drawRect] on the PDF page.
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Offset normToSlide(double nx, double ny, Rect drawRect) =>
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Offset(drawRect.left + nx * drawRect.width,
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drawRect.top + ny * drawRect.height);
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/// Absolute pen width (PDF units) for a stroke whose width is a fraction of the
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/// page width, scaled into [drawRect].
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double slideStrokeWidth(double normalizedWidth, Rect drawRect) =>
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normalizedWidth * drawRect.width;
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