Question

想象一下使用单个位图水平和垂直平铺图块的画布，例如：

以上是通过以下方式实现的：

procedure TForm1.PaintBox1Paint(Sender: TObject);
var
  X, Y: Integer;
begin
  Y := 0;
  while Y < PaintBox1.Height do
  begin
    X := 0;
    while X < PaintBox1.Width do
    begin
      PaintBox1.Canvas.Draw(X, Y, Image1.Picture.Bitmap);
      Inc(X, Image1.Picture.Bitmap.Width);
    end;
    Inc(Y, Image1.Picture.Bitmap.Height);
  end;

  PaintBox1.Canvas.Brush.Style := bsClear;
  PaintBox1.Canvas.Rectangle(PaintBox1.ClientRect);
end;

现在我想做的是扩展上面的内容以允许水平和垂直偏移来模拟使用滚动条等时平铺图像被包裹/滚动的效果。

这个想法是，当更改水平偏移时，例如，平铺图像将向左移动，从右侧您应该看到平铺图像看起来好像它们已经从绘图框的一侧缠绕到其他

我已经设法制作了一个测试项目，它确实按照我想要的方式工作，它看起来像这样：

我已经在Lazarus中编写了这个测试项目，但它很容易适应Delphi中的测试。

以下是lfm：

object Form1: TForm1
  Left = 0
  Height = 625
  Top = 0
  Width = 782
  Caption = 'Form1'
  ClientHeight = 625
  ClientWidth = 782
  OnCreate = FormCreate
  Position = poScreenCenter
  Visible = False
  object Label1: TLabel
    Left = 25
    Height = 15
    Top = 16
    Width = 40
    Caption = 'Regular'
    ParentColor = False
  end
  object Label2: TLabel
    Left = 361
    Height = 15
    Top = 16
    Width = 32
    Caption = 'Offset'
    ParentColor = False
  end
  object PaintBox1: TPaintBox
    Left = 24
    Height = 320
    Top = 40
    Width = 320
    OnPaint = PaintBox1Paint
  end
  object PaintBox2: TPaintBox
    Left = 361
    Height = 320
    Top = 40
    Width = 320
    OnPaint = PaintBox2Paint
  end
  object Image1: TImage
    Left = 25
    Height = 48
    Top = 544
    Width = 48
    AutoSize = True
    Picture.Data = {
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    }
    Visible = False
  end
  object Label3: TLabel
    Left = 645
    Height = 15
    Top = 376
    Width = 36
    Alignment = taRightJustify
    AutoSize = False
    Caption = '0'
    ParentColor = False
  end
  object ScrollBar1: TScrollBar
    Left = 361
    Height = 17
    Top = 374
    Width = 273
    Max = 5000
    PageSize = 0
    TabOrder = 0
    OnChange = ScrollBar1Change
  end
  object ScrollBar2: TScrollBar
    Left = 696
    Height = 320
    Top = 40
    Width = 17
    Kind = sbVertical
    Max = 5000
    PageSize = 0
    TabOrder = 1
    OnChange = ScrollBar2Change
  end
  object Label4: TLabel
    Left = 720
    Height = 15
    Top = 40
    Width = 34
    Caption = 'Label4'
    ParentColor = False
  end
end

和来源

unit Unit1;

{$mode delphi}

interface

uses
  Classes, SysUtils, FileUtil, Forms, Controls, Graphics, Dialogs, StdCtrls,
  ExtCtrls;

{ TForm1 }

type
  TForm1 = class(TForm)
    Image1: TImage;
    Label1: TLabel;
    Label2: TLabel;
    Label3: TLabel;
    Label4: TLabel;
    PaintBox1: TPaintBox;
    PaintBox2: TPaintBox;
    ScrollBar1: TScrollBar;
    ScrollBar2: TScrollBar;
    procedure FormCreate(Sender: TObject);
    procedure PaintBox1Paint(Sender: TObject);
    procedure PaintBox2Paint(Sender: TObject);
    procedure ScrollBar1Change(Sender: TObject);
    procedure ScrollBar2Change(Sender: TObject);
  private
    FOffsetX: Integer;
    FOffsetY: Integer;
  public
    { public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.lfm}

{ TForm1 }

procedure TForm1.FormCreate(Sender: TObject);
begin
  FOffsetX := 0;
  FOffsetY := 0;
end;

procedure TForm1.PaintBox1Paint(Sender: TObject);
var
  X, Y: Integer;
begin
  Y := 0;
  while Y < PaintBox1.Height do
  begin
    X := 0;
    while X < PaintBox1.Width do
    begin
      PaintBox1.Canvas.Draw(X, Y, Image1.Picture.Bitmap);
      Inc(X, Image1.Picture.Bitmap.Width);
    end;
    Inc(Y, Image1.Picture.Bitmap.Height);
  end;

  PaintBox1.Canvas.Brush.Style := bsClear;
  PaintBox1.Canvas.Rectangle(PaintBox1.ClientRect);
end;

// needs improvement
procedure TForm1.PaintBox2Paint(Sender: TObject);
var
  X, Y: Integer;
begin
  Y := -FOffsetY;
  while Y < PaintBox2.Height do
  begin
    X := -FOffsetX;
    while X < PaintBox2.Width do
    begin
      PaintBox2.Canvas.Draw(X, Y, Image1.Picture.Bitmap);
      Inc(X, Image1.Picture.Bitmap.Width);
    end;
    Inc(Y, Image1.Picture.Bitmap.Height);
  end;

  PaintBox2.Canvas.Brush.Style := bsClear;
  PaintBox2.Canvas.Rectangle(PaintBox2.ClientRect);
end;

procedure TForm1.ScrollBar1Change(Sender: TObject);
begin
  FOffsetX := ScrollBar1.Position;
  Label3.Caption := IntToStr(FOffsetX);
  PaintBox2.Invalidate;
end;

procedure TForm1.ScrollBar2Change(Sender: TObject);
begin
  FOffsetY := ScrollBar2.Position;
  Label4.Caption := IntToStr(FOffsetY);
  PaintBox2.Invalidate;
end;

end.

我的问题是如何改进我现有的代码以及是否有更好的方法来实现这一点，我可能会使任务变得复杂？

对于小偏移，绘制框的绘制速度非常快但是有较大的偏移量，例如5000（我目前正在测试），滚动变得相当慢，我想知道我是否错过了一些明显的东西？

Answer 1

无需绘制所有不可见的位图。对于任何给定的位图宽度/高度（让我们称之为＆＃34; tile＆＃34;），您只需要在画布边缘以外的最多1个图块宽度或高度开始/完成绘图。 / p>

即。计算第一个可见的瓷砖并开始绘画。

上图试图显示我的意思...只有绿色瓷砖位于可见区域（蓝色阴影），所以即使偏移包括那些显示为红色的，也没有点绘制它们。

Windows（操作系统）无论如何都会剪切这些内容，但是你仍然花时间在那些不可见的磁贴上进行迭代，这就是为什么你的较大偏移导致性能下降的原因......你花时间计算＆＃ 34不可见＃34;空间，在到达实际需要绘制的图块之前。

计算＆＃34;起源＆＃34;在哪里开始绘画是简单的算术，并不需要循环迭代。不是将 Y 和 X 初始化为绝对偏移，而是使用简单的 mod将它们设置为该偏移量的平铺高度/宽度的第一个倍数操作：

Y := -FOffsetY mod Image1.Height;

X := -FOffseXY mod Image1.Width;

或类似的

Jerry的观察w.r.t使用屏幕外的位图然后blitting到你的控件也将优化实际绘画。

如何创建一个不慢的包裹/滚动平铺区域？

1 个答案: