Implement missing Microsoft.Maui.Graphics platform support#12
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Phase 1 - Fix core drawing correctness: - Rewrite DrawPathInternal to handle all PathOperation segment types (Move, Line, Cubic bezier, Quad bezier, Arc, Close) using PathF.GetSegmentType/GetPointsForSegment API - Apply stroke properties (dash patterns, line caps/joins, miter limit) to Cairo context in ApplyStroke() - Replace fake GetStringSize (length*fontSize*0.6) with proper Cairo TextExtents/FontExtents measurement - Implement gradient paint support (LinearGradientPaint, RadialGradientPaint) via cairo_pattern_create_linear/radial P/Invoke - Implement text alignment (horizontal/vertical) and font weight/style in DrawString using text/font extents for positioning Phase 2 - Complete missing canvas operations: - Implement ConcatenateTransform via Cairo.Matrix.Init + cr.Transform - Implement DrawImage with CairoPlatformImage (IImage backed by Cairo.ImageSurface) including Downsize, Resize, Save, FromStream - Apply Antialias and BlendMode properties to Cairo context - Implement SubtractFromClip via even-odd fill rule trick - Store SetShadow parameters (rendering deferred to future work) Phase 3 - GraphicsView interaction events: - Wire GestureClick for StartInteraction/EndInteraction/CancelInteraction - Wire GestureDrag for DragInteraction - Wire EventControllerMotion for hover events Architecture: - Extract CairoCanvas from GraphicsViewHandler.cs to dedicated Graphics/CairoCanvas.cs file (grew from ~280 to ~660 lines) - Add Graphics/CairoPlatformImage.cs implementing IImage + IDrawable Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Phase 3 - Platform services: - CairoStringSizeService (IStringSizeService): Text measurement using temporary Cairo surface + TextExtents/FontExtents - CairoBitmapExportService (IBitmapExportService): Creates CairoBitmapExportContext backed by Cairo ImageSurface with ICanvas and IImage properties, plus WriteToStream via PNG export - CairoImageLoadingService (IImageLoadingService): Loads images from streams via CairoPlatformImage.FromStream All three registered as singletons in AppHostBuilderExtensions.cs. Shadow rendering: - SetShadow now stores offset/blur/color and DrawShadowFill renders offset copies with decreasing alpha to approximate blur for fill operations (FillRectangle, FillRoundedRectangle, FillEllipse, FillPath) Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Adds a comprehensive demo page to the sample app with 9 IDrawable sections that exercise every graphics feature implemented for issue #11: 1. Path operations: cubic bezier, quadratic bezier, arc, closed paths 2. Stroke properties: dash patterns, line caps (butt/round/square), line joins (miter/round/bevel) 3. Gradient paint: linear gradient, radial gradient, gradient on path 4. Text features: horizontal/vertical alignment, font weight/style, GetStringSize measurement 5. ConcatenateTransform: rotation, scale, skew, composite transforms 6. Shadow rendering: shadows on rect, rounded rect, ellipse, path 7. Antialias & BlendMode: aliased vs antialiased, Xor and DestOver 8. SubtractFromClip: ClipRectangle, SubtractFromClip, ClipPath 9. Interaction events: StartInteraction, EndInteraction, DragInteraction, hover events with live log display Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Upgrades all text rendering in CairoCanvas from Cairo's toy font API (ShowText/TextExtents/SelectFontFace) to PangoCairo layout: Text rendering: - DrawString uses Pango.Layout with word wrapping via SetWidth/SetWrap - Horizontal alignment via Pango.Alignment (Left/Center/Right) - Vertical alignment computed from GetPixelSize (Top/Center/Bottom) - lineSpacingAdjustment applied via SetSpacing - Font weight/style via Pango.FontDescription (SetWeight/SetStyle) - TextFlow.ClipBounds clips to bounding rectangle Text measurement: - GetStringSize uses Pango.Layout.GetPixelSize for accurate sizing - CairoStringSizeService updated to use PangoCairo instead of Cairo IAttributedText support: - DrawText builds PangoAttrList from IAttributedTextRun attributes - Supports Bold, Italic, Underline, Strikethrough, FontSize, Color - Correct UTF-8 byte index conversion for attribute ranges Sample app: - Added section 10 (Multi-line Text Wrapping) to GraphicsFeaturePage - Shows wrapped text with Left/Top, Center/Center, Right/Bottom alignment Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
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Summary
Addresses #11 — implements the missing platform layer for the GTK4 backend.
What changed
New files:
Graphics/CairoCanvas.cs— FullICanvasimplementation backed by Cairo + PangoCairo text layoutGraphics/CairoPlatformImage.cs—IImageimplementation backed byCairo.ImageSurfaceGraphics/CairoGraphicsServices.cs— Platform services:IStringSizeService,IBitmapExportService,IImageLoadingServicePages/GraphicsFeaturePage.cs— Comprehensive demo page exercising all graphics features (10 sections)Modified:
Handlers/GraphicsViewHandler.cs— Uses extracted CairoCanvas; adds interaction eventsHosting/AppHostBuilderExtensions.cs— Registers graphics platform servicesPhase 1 — Core drawing fixes
Phase 2 — Missing canvas operations
Phase 3 — Platform services and effects
Phase 4 — Pango text layout
Still TODO (future PRs)