TFPCustomBrush

TFPCustomBrush is a fundamental property of TFPCustomCanvas and defines how a geometric shape is filled in fcl-image.

Properties

• Canvas: points to the TFPCustomCanvas on which the brush operates. The property is inherited from the ancestor TFPCanvasHelper.
• FPColor: specifies the basic color (type TFPColor) used to fill the shape (inherited from ancestor TFPCanvasHelper).
• Style: an enumeration of type TFPBrushStyle which defines the pattern used for filling:
  • bsClear: no filling at all, FPColor is ignored.
  • bsSolid: uniform fill of the shape with the FPColor specified
  • The following styles define hatch patterns which are drawn in the FPColor specified. The background between the hatch lines is left empty, it can only be filled by drawing the shape with bsSolid before.
    • bsHorizontal, bsVertical, bsFDiagonal, bsBDiagonal define a single-line hatch pattern.
    • bsCross and bsDiagCross define a crossed pattern.
  • bsImage: fills the shape by tiling the picture given in property Image on the canvas.
  • bsPattern: uses a custom pattern to fill the shape. The pattern is given by property Pattern. See below.
• Image: specifies the image (type TFPCustomImage) used when Style is bsImage. The alpha channel is respected.
• Pattern: specifies the custom pattern for filling the shape when Style is bsPattern. The pattern is defined as a 32-element array of LongInt values. This sets up a matrix of 32x32 bits. Each one-bit corresponds to a colored pixel. Pixels corresponding to zero-bits are not drawn.

These properties are applied in all subsequent drawing commands.

  Note: The advanced styles bsImage and bsPattern are availabel for non-rectangular shapes only for FPC v3.3.1+

Methods

• function CopyBrush: TFPCustomBrush: creates a new brush and copies the current properties to it.

Sample code

Filling a circle with an image pattern (bsImage)

program project1;

uses
  classes, FPImage, FPCanvas, FPImgCanv, FPReadPNG, FPWritePNG;

var
  image: TFPCustomImage;
  pattern: TFPCustomImage;
  canvas: TFPCustomCanvas;
  writer: TFPCustomImageWriter;

begin
  // "pattern.png" is some png image (with alpha channel).
  // Select one from the Lazarus image collection in (lazarus)/images
  pattern := TFPMemoryImage.Create(0, 0);
  pattern.LoadFromFile('pattern.png');

  image := TFPMemoryImage.Create(200,200);
  try
    canvas := TFPImageCanvas.Create(image);
    try
      // Set the pen style
      canvas.Pen.Mode    := pmCopy;
      canvas.Pen.Style   := psSolid;
      canvas.Pen.Width   := 1;
      canvas.Pen.FPColor := colWhite;

      // Set the brush for the circle: the image stored in "pattern"
      canvas.Brush.Style := bsImage;
      canvas.Brush.Image := pattern;
      // Draw a circle filled by "pattern"
      canvas.Ellipse(10, 10, 90, 90);

      // Save to file
      writer := TFPWriterPNG.Create;
      try
        // Activate alpha channel in saved image
        TFPWriterPNG(writer).UseAlpha := true;
        // Write image to file
        image.SaveToFile('DrawTest.png', writer);
      finally
        writer.Free;
      end;

    finally
      canvas.Free;
    end;

  finally
    pattern.Free;
    image.Free;
  end;
end.

Filling a rectangle with a custom pattern (bsPattern)

program project1;

uses
  classes, sysutils,
  FPImage, FPCanvas, FPImgCanv, FPWritePNG;

const
  BIT_PATTERN: TBrushPattern = (
    %11111111111111111111111111111111,      // 1
    %11111111111000000000001111111111,      // 2
    %11111111110000000000000111111111,      // 3
    %11111111100000000000000011111111,      // 4
    %11111111000000000000000001111111,      // 5
    %11111110000000000000000000111111,      // 6
    %11111100000000000000000000011111,      // 7
    %11111000000000000000000000001111,      // 8
    %11110000000000000000000000000111,      // 9
    %11100000000000000000000000000011,      // 10
    %11000000000000001000000000000001,      // 11
    %10000000000000011100000000000000,      // 12
    %10000000000000111110000000000000,      // 13
    %10000000000001111111000000000000,      // 14
    %10000000000011110111100000000000,      // 15
    %10000000000111100011110000000000,      // 16
    %10000000000011110111100000000000,      // 17
    %10000000000001111111000000000000,      // 18
    %10000000000000111110000000000000,      // 19
    %10000000000000011100000000000000,      // 20
    %10000000000000001000000000000000,      // 21
    %10000000000000000000000000000000,      // 22
    %11000000000000000000000000000001,      // 23
    %11100000000000000000000000000011,      // 24
    %11110000000000000000000000000111,      // 25
    %11111000000000000000000000001111,      // 26
    %11111100000000000000000000011111,      // 27
    %11111110000000000000000000111111,      // 28
    %11111111000000000000000001111111,      // 29
    %11111111100000000000000011111111,      // 30
    %11111111110000000000000111111111,      // 31
    %11111111111000000000001111111111       // 32
  );

var
  image: TFPCustomImage;
  canvas: TFPCustomCanvas;
  writer: TFPCustomImageWriter;

begin
  image := TFPMemoryImage.Create(200, 200);
  try
    canvas := TFPImageCanvas.Create(image);
    try
      // Set the pen style
      canvas.Pen.Mode    := pmCopy;
      canvas.Pen.Style   := psSolid;
      canvas.Pen.Width   := 3;
      canvas.Pen.FPColor := colNavy;

      // Set the brush for the rectangle: a bit pattern
      // Unless the shape should be transparent draw the background first
      canvas.Brush.Style := bsSolid;
      canvas.Brush.FPColor := colYellow;
      canvas.Rectangle(10, 110, 190, 190);
      // Now draw the pattern
      canvas.Brush.Style := bsPattern;
      canvas.Brush.FPColor := colBlue;  // Color for every set bit (1) in the pattern
      canvas.Brush.Pattern := BIT_PATTERN;
      canvas.Rectangle(10, 110, 190, 190);

      // Save to file
      writer := TFPWriterPNG.Create;
      try
        // Activate alpha channel in saved image
        TFPWriterPNG(writer).UseAlpha := true;
        // Write image to file
        image.SaveToFile('DrawTest.png', writer);
      finally
        writer.Free;
      end;

    finally
      canvas.Free;
    end;
  finally
    image.Free;
  end;
end.