Skia4Delphi is a cross-platform 2D graphics API for Delphi based on Google's Skia graphics library.

About

Skia is a great open source library for drawing 2D Text, Geometries, Images, focused on accurate, high quality and high performance rendering, which provides common APIs that work across a variety of hardware and software platforms.

Google's Skia Graphics Library serves as the graphics engine for Google Chrome and Chrome OS, Android, Flutter, Xamarin, Mozilla Firefox and Firefox OS, and many other products.

Features

• Canvas 2D and Text Layout;
• CPU software rasterization;
• GPU-accelerated rendering;
• Right-to-Left rendering;
• SVG rendering and creation;
• PDF output;
• Runtime effects;
• Shading language;
• Shaders, mask and color filters;
• Image and path effects;
• Animated image player; (Lottie, GIF, WebP)
• Image codecs; (bmp, gif, ico, jpg, png, wbmp, webp and raw images)
• Particles; (provides a way to quickly generate large numbers of drawing primitives with dynamic, animated behavior) and much more...

FMX graphics engine replacement

Using the Skia4Delphi library it is possible to override Firemonkey's rendering engine so that it can use Skia as its default Canvas. With that, your Firemonkey application will automatically:

• Draw with antialiasing on any platform (the drawing quality is based on the Form.Quality property);
• Increase the overall graphics performance of your application by up to 50% (even drawing with higher quality);
• Resize images with better quality (also based on Form.Quality);
• Support Right-To-Left text rendering;
• Fix dozens of inconsistencies in drawings (especially in corners and strokes, such as dashes, and in texts with special emojis);
• Increase the performance of the library in general (controls, drawings, among others...).

Learn more...

Summary

• Using the library
  • Prerequisites
    • Install
    • Enable Skia
  • Examples
    • Basic usage
    • Text Right-to-Left
    • Custom fonts
    • PDF
    • Codecs
• Integration with Delphi
  • Bitmap
  • Image formats
  • FMX Canvas
    • Enable Canvas
    • Benchmark
    • Surface
    • Controls
    • Right-to-Left
• Controls VCL/FMX
  • TSkAnimatedImage
  • TSkLabel
  • TSkPaintBox
  • TSkSvg
    • Limitations
• Compatibility
• Documentation
• Version

Using the library

Prerequisites

Install

You can install Skia4Delphi in 3 ways:

• Setup (recommended)

  Download the setup of latest release and install it.

  

• Embarcadero's GetIt (RAD Studio > Tools > GetIt Package Manager...)

  

  

• Chocolatey package manager

  choco install skia4delphi

Remarks

1. Manual installation is possible, although it is not recommended; Learn more...
2. The pre-built Skia binaries were included in the source, but you can easily recompile them; Learn more...

Enable Skia

After install the Skia4Delphi, just right click in your application project and click Enable Skia.

Tip

To improve the quality and performance of FMX drawings, replace the FMX graphics engine with the Skia4Delphi graphic engine. Learn more...

Examples

In this section you will find some examples of using Skia4Delphi, it works in Console, FMX, and VCL applications. The code below is common code among all the examples in this section:

uses
  Skia;

type
  TSkDrawExampleProc = reference to procedure(const ACanvas: ISkCanvas; const ADest: TRectF);

procedure DrawExample(const AWidth, AHeight: Integer; const ADrawProc: TSkDrawExampleProc);
var
  LSurface: ISkSurface;
begin
  LSurface := TSkSurface.MakeRaster(AWidth, AHeight);
  LSurface.Canvas.Clear(TAlphaColors.Null);
  ADrawProc(LSurface.Canvas, RectF(0, 0, AWidth, AHeight));
  LSurface.MakeImageSnapshot.EncodeToFile('output.png');
end;

Basic usage

The code below demonstrate how to draw shapes:

DrawExample(256, 256,
  procedure (const ACanvas: ISkCanvas; const ADest: TRectF)
  var
    LOval: ISkRoundRect;
    LPaint: ISkPaint;
    LRect: TRectF;
  begin
    LPaint := TSkPaint.Create;
    LPaint.AntiAlias := True;

    LPaint.Color := $FF4285F4;
    LRect := TRectF.Create(PointF(10, 10), 100, 160);
    ACanvas.DrawRect(LRect, LPaint);

    LOval := TSkRoundRect.Create;
    LOval.SetOval(LRect);
    LOval.Offset(40, 80);
    LPaint.Color := $FFDB4437;
    ACanvas.DrawRoundRect(LOval, LPaint);

    LPaint.Color := $FF0F9D58;
    ACanvas.DrawCircle(180, 50, 25, LPaint);

    LRect.Offset(80, 50);
    LPaint.Color := $FFF4B400;
    LPaint.Style := TSkPaintStyle.Stroke;
    LPaint.StrokeWidth := 4;
    ACanvas.DrawRoundRect(LRect, 10, 10, LPaint);
  end);

This code results in the output below:

Learn more...

Text Right-to-Left

There are a couple of languages that the direction of the text is from right to left such as Persian, Arabic, Hebrew, and more. With Skia4Delphi it is possible to render Right-to-Left. The example below demonstrates how to render a Persian sentence using a text-shaping engine:

DrawExample(256, 256,
  procedure (const ACanvas: ISkCanvas; const ADest: TRectF)
  var
    LBlob: ISkTextBlob;
    LFont: ISkFont;
    LPaint: ISkPaint;
    LShaper: ISkShaper;
  begin
    LFont := TSkFont.Create(TSkTypeface.MakeDefault, 55, 1);
    LShaper := TSkShaper.Create;
    LBlob := LShaper.Shape('سلام دنیا!', LFont, False, High(Integer));

    LPaint := TSkPaint.Create;
    LPaint.AntiAlias := True;
    LPaint.Color := TAlphaColors.Tomato;

    ACanvas.DrawTextBlob(LBlob, 0, 0, LPaint);
  end);

This code results in the output below:

Custom fonts

With Skia4Delphi it is possible to use custom fonts easily, from the file, without the need to install it on the operating system, regardless of the platform. The example below will draw using two custom fonts:

DrawExample(256, 256,
  procedure (const ACanvas: ISkCanvas; const ADest: TRectF)
  var
    LFont: ISkFont;
    LPaint: ISkPaint;
  begin
    LFont := TSkFont.Create(TSkTypeface.MakeFromFile('Samples\Demo\Assets\nunito-extrabold.ttf'), 23);
    LPaint := TSkPaint.Create;
    LPaint.Shader := TSkShader.MakeGradientLinear(PointF(0, 0), PointF(256, 145), $FFFF5F5F, $FF5B8DFE, TSkTileMode.Clamp);

    ACanvas.DrawSimpleText('"Each dream that you', 2, 25, LFont, LPaint);
    ACanvas.DrawSimpleText('leave behind is a part', 2, 55, LFont, LPaint);
    ACanvas.DrawSimpleText('of your future that will', 2, 85, LFont, LPaint);
    ACanvas.DrawSimpleText('no longer exist."', 2, 115, LFont, LPaint);

    LFont := TSkFont.Create(TSkTypeface.MakeFromFile('Samples\Demo\Assets\bonheur-royale-regular.ttf'), 28);
    LPaint.Shader := nil;
    LPaint.Color  := $FF5B8DFE;
    ACanvas.DrawSimpleText('(Steve Jobs)', 2, 150, LFont, LPaint);
  end);

This code results in the output below:

PDF

With Skia4Delphi it is possible to create PDF documents and draw anything on them, from text to images. The example below demonstrates how to create an PDF document and draw an SVG inside it:

var
  LCanvas: ISkCanvas;
  LDocument: ISkDocument;
  LDocumentStream: TStream;
  LSVGDOM: ISkSVGDOM;
  LSize: TSizeF;
begin
  LSVGDOM := TSkSVGDOM.MakeFromFile('Samples\Demo\Assets\lion.svg');
  LSize := TSizeF.Create(600, 600);
  LSVGDOM.SetContainerSize(LSize);

  LDocumentStream := TFileStream.Create('output.pdf', fmCreate);
  try
    LDocument := TSkDocument.MakePDF(LDocumentStream);
    try
      LCanvas := LDocument.BeginPage(LSize.Width, LSize.Height);
      try
        LSVGDOM.Render(LCanvas);
      finally
        LDocument.EndPage;
      end;
    finally
      LDocument.Close;
    end;
  finally
    LDocumentStream.Free;
  end;
end;

This code results in the output below:

Codecs

The Skia4Delphi library supports many image formats. See below the list:

• Supported formats for decoding

  Image Format	Extensions
  Bitmap	.bmp
  GIF	.gif
  Icon	.ico
  JPEG	.jpg, .jpeg
  PNG	.png
  Raw Adobe DNG Digital Negative	.dng
  Raw Canon	.cr2
  Raw Fujifilm RAF	.raf
  Raw Nikon	.nef, .nrw
  Raw Olympus ORF	.orf
  Raw Panasonic	.rw2
  Raw Pentax PEF	.pef
  Raw Samsung SRW	.srw
  Raw Sony	.arw
  WBMP	.wbmp
  WebP	.webp

  Note: Raw images are limited to non-windows platforms

• Supported formats for encoding

  Image Format	Extensions
  JPEG	.jpg, .jpeg
  PNG	.png
  WebP	.webp

About WebP

WebP is a modern image format that provides superior lossless and lossy compression for images. WebP lossless images are 26% smaller in size compared to PNGs. WebP lossy images are 25-34% smaller than comparable JPEG images at equivalent quality.

The example below demonstrates how to encoder to WebP format:

var
  LImage: ISkImage;
begin
  LImage := TSkImage.MakeFromEncodedFile('Samples\Demo\Assets\kung-fu-panda.png');
  LImage.EncodeToFile('output.webp', TSkEncodedImageFormat.WEBP, 80);
  LImage.EncodeToFile('output.jpg', TSkEncodedImageFormat.JPEG, 80);
end;

This code results in the output below:

Integration with Delphi

Bitmap

It is possible to edit TBitmap (VCL or FMX) with Skia's Canvas using the code below:

var
  LBitmap: TBitmap;
begin
  LBitmap := TBitmap.Create(100, 100);
  try
    LBitmap.SkiaDraw(
      procedure (const ACanvas: ISkCanvas)
      begin
        // Draw with Skia canvas...
      end);

Image formats

The library registers the following codecs:

• VCL: .svg, .webp, .wbmp and raw images (.arw, .cr2, .dng, .nef, .nrw, .orf, .raf, .rw2, .pef and .srw).

• FMX: .bmp, .gif, .ico, .webp, .wbmp and raw images (.arw, .cr2, .dng, .nef, .nrw, .orf, .raf, .rw2, .pef and .srw).

As a result, any Delphi control, such as a TImage, can normally load these new formats.

FMX Canvas

It is possible to replace the default Canvas from FMX to Skia based Canvas. Once this feature is enabled, all FMX controls will be painted using Skia4Delphi automatically. With that it is possible to improve the quality and performance of the drawings for the FMX as well as for the whole library.

Enable Canvas

Open the source of your Delphi Application Project (.dpr), include the Skia.FMX unit after the FMX.Forms unit, and set the GlobalUseSkia to True, as in the example below:

uses
  System.StartUpCopy,
  FMX.Forms,
  Skia.FMX,
  Unit1 in 'Unit1.pas' {Form1};

{$R *.res}

begin
  GlobalUseSkia := True;
  Application.Initialize;
  ...

Remarks

1. Skia.FMX unit must be included after the FMX.Forms;
2. The Metal implementation is experimental, but can be used by including the FMX.Types unit after the FMX.Forms unit, and setting GlobalUseMetal to True together with GlobalUseSkia;
3. GlobalUseSkia has no effect on Linux. (although not supported, all controls work perfectly)
4. This declaration of GlobalUseSkia := True;, as well as other variables of FMX itself, such as GlobalUseMetal, can also be made in the initialization of some unit instead of .dpr. Sometimes this is really necessary because if in the initialization or in the class constructor of some unit, bitmaps are used, the GlobalUseXXX declarations of the .dpr will have no effect. In this case, just create a unit in the project like "Project.Startup.pas", place the GlobalUseXXX declarations in the initialization of this new unit, and declare this new unit before any other unit of yours in the .dpr, that is, right after FMX.Forms.

Benchmark

The performance test is a simulation of a real application, with hundreds of controls, to measure the FPS rate when sliding a vertical scroll.

Metal

Remarks

1. Delphi's TGPUCanvas (default Canvas used on cell phones, as well as Apple computers when Metal is enabled) does not use anti-aliasing (anti-aliasing is a technique that improves the quality of diagonal lines) while Skia uses it. That is, Skia has better performance and quality in the drawings than default FMX Canvas.

   FMX circle	Skia circle

2. Firemonkey uses Quartz on macOS, and for Skia4Delphi use OpenGL it would be necessary to edit the Delphi runtime library, so we choose to keep the rasterization method and not implement OpenGL on macOS. In the future it is likely that we will set Metal as default, as OpenGL is deprecated in Apple's operating systems. For those who want to use the Skia Canvas on macOS we recommend enabling Metal.

3. Tests made from virtual machines are inconsistent with reality.

Surface

Using Skia's Canvas, during the Scene of a Bitmap or Control (between the BeginScene and EndScene calls), it is possible to access the Surface property as follows:

uses
  Skia,
  Skia.FMX.Graphics;

var
  LBitmap: TBitmap;
  LCanvas: ISkCanvas;
begin
  LBitmap := TBitmap.Create(300, 300);
  try
    if LBitmap.Canvas.BeginScene then
    begin
      try
        LCanvas := TSkCanvasCustom(LBitmap.Canvas).Surface.Canvas;
        // Draw with LCanvas...
      finally
        LBitmap.Canvas.EndScene;
      end;
    end;
  finally
    LBitmap.Free;
  end;
end;

Remarks

1. Surface property will only be available during Scene (between the BeginScene and EndScene calls);
2. Canvas for UI (created from a window eg rectangles, circles, objects inherited from TControl) must draw exclusively from the main thread, while Canvas created from TBitmap are thread safe.

Tip

If your app has background threads that do a lot of bitmap drawings, be aware that it is safe to remove the global lock from the TCanvas base class when Skia based Canvas is enabled, to allow your app to do truly parallel drawings, gaining a lot of performance. For that, it is necessary to make a patch in the units FMX.Graphics.pas and FMX.TextLayout.pas. Learn more

Controls

Using Skia's Canvas, it is possible to access the Surface property from the Paint procedure of a control, to draw directly using Skia, as shown below:

unit Unit1;

interface

uses
  FMX.Controls,
  FMX.Graphics,
  Skia,
  Skia.FMX.Graphics;


type
  TControl1 = class(TControl)
  protected
    procedure Paint; override;
  end;

implementation

{ TControl1 }

procedure TControl1.Paint;
var
  LCanvas: ISkCanvas;
begin
  LCanvas := TSkCanvasCustom(Canvas).Surface.Canvas;
  // Draw with LCanvas...
end;

Right-to-Left

Using Skia's Canvas, your application will now support Right-To-Left text rendering. But for that you will need to make 3 changes to your project:

1. Open the source of your Delphi Application Project (.dpr), include the line Application.BiDiMode := TBiDiMode.bdRightToLeft;, like below:

program Project1;

uses
  System.StartUpCopy,
  FMX.Forms,
  System.Classes,
  Skia.FMX,
  Unit1 in 'Unit1.pas' {Form1};

{$R *.res}

begin
  Application.BiDiMode := TBiDiMode.bdRightToLeft;
  GlobalUseSkia := True;
  Application.Initialize;
  Application.CreateForm(TForm1, Form1);
  Application.Run;
end.

2. Set the property BiDiMode of your forms to bdRightToLeft;
3. Keyboard input controls like TEdit and TMemo, need to be fixed by Embarcadero, meanwhile, as a workaround, set the ControlType property of these controls to Platform.

Controls VCL/FMX

TSkAnimatedImage

TSkAnimatedImage is the control that can load and render animated images, including vector animations, in a very simple way. The supported formats are:

The example below demonstrates how to play lottie files using TSkAnimatedImage:

var
  LAnimatedImage: TSkAnimatedImage;
begin
  LAnimatedimage := TSkAnimatedImage.Create(Self);
  LAnimatedimage.LoadFromFile('Samples\Demo\Assets\rocket.json');
  LAnimatedimage.Parent := Self;
end;

The example above results in the output below:

Learn more...

TSkLabel

TSkLabel is the control that implements the SkParagraph internally, having several more features than the TLabel, such as:

• Font families; (font fallback list like in css)
• Font weight;
• Font slant;
• Support for multiple styles in text;
• Support for BiDi; (Right-to-Left)
• Support justify horizontal alignment;
• Support custom font; (without install the font)
• Supports background color on parts of the text;
• Limit the maximum number of lines;
• Auto size option; (width and height)
• Advanced decorations; (like underline wavy, overline, dashed line, among others...) and much more...

Learn more...

TSkPaintBox

TSkPaintBox is the ideal control for painting with skia api directly on the canvas with the event OnDraw:

procedure TForm1.SkPaintBox1Draw(ASender: TObject; const ACanvas: ISkCanvas;
  const ADest: TRectF; const AOpacity: Single);
var
  LPaint: ISkPaint;
begin
  LPaint := TSkPaint.Create;
  LPaint.Shader := TSkShader.MakeGradientSweep(ADest.CenterPoint,
    [$FFFCE68D, $FFF7CAA5, $FF2EBBC1, $FFFCE68D]);
  ACanvas.DrawPaint(LPaint);
end;

The example above results in the output below:

Note: The TSkPaintBox has a drawing caching system. To force a drawing refresh, call TSkPaintBox.Redraw. However, this cache system does not exist in FMX apps that have enabled Skia4Delphi graphic engine for optimization reasons.

TSkSvg

TSkSvg is the control to load and display SVG easily:

var
  LSvg: TSkSvg;
begin
  LSvg := TSkSvg.Create(Self);
  LSvg.Svg.Source := TFile.ReadAllText('Samples\Demo\Assets\gorilla.svg');
  LSvg.Parent := Self;
end;

The example above results in the output below:

Learn more...

Compatibility

For the platforms supported by Skia4Delphi (listed above), the OS versions supported by the library are the same OS versions that RAD Studio supports.

Documentation

The APIs are very similar to Skia's, few methods and functions have been renamed for readability, so the Skia documentation can be used.

Version

Skia4Delphi 4.0.2

Skia Version used: chrome/m107

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