Firemonkey 图片显示拉伸不变形
Firemonkey 实现简单的图片拉伸不变形，是利用原始图片的 "固定区" 及 "位伸区" 来达到此目的，因此必需要有此结构的图片才适合。
下面以聊天气泡为例，下图四个角为固定区，就是拉伸时，这四个区是不变的，而拉伸区，会自动依位伸的大小自动位伸：
实作效果：
代码，直接扩展 Canvas 功能：
//------------------------------------------------------------------------------ // Design by 龟山阿卍 - // http://www.cnblogs.com/onechen/ - //------------------------------------------------------------------------------ unit FMX.Graphics.Helper; interface uses System.Types, FMX.Graphics; type TCanvasHelper = class helper for TCanvas // 图片四角张缩 procedure DrawBitmapCapInsets( const Bitmap1: TBitmap; // 图片 const DesRect: TRectF; // 目的区域 const CapInsetsRect: TRectF; // 四角区域 const Opacity: Single = 1.0; // 透明度 const HighSpeed: Boolean = False); // 高速 end; implementation // 图片四角张缩 procedure TCanvasHelper.DrawBitmapCapInsets( const Bitmap1: TBitmap; // 图片 const DesRect: TRectF; // 目的区域 const CapInsetsRect: TRectF; // 四角区域 const Opacity: Single = 1.0; // 透明度 const HighSpeed: Boolean = False); // 高速 var SrcRect: TRectF; begin SrcRect := RectF(0, 0, Bitmap1.Width, Bitmap1.Height); //------------------------------------------------------------------------- // 最内圈 (不张缩) - //------------------------------------------------------------------------- // 左上 Self.DrawBitmap(Bitmap1, RectF(SrcRect.Left, SrcRect.Top, SrcRect.Left + CapInsetsRect.Left, SrcRect.Top + CapInsetsRect.Top), RectF(DesRect.Left, DesRect.Top, DesRect.Left + CapInsetsRect.Left, DesRect.Top + CapInsetsRect.Left), Opacity, HighSpeed); // 右上 Self.DrawBitmap(Bitmap1, RectF(SrcRect.Right - CapInsetsRect.Right, SrcRect.Top, SrcRect.Right, SrcRect.Top + CapInsetsRect.Top), RectF(DesRect.Right - CapInsetsRect.Right, DesRect.Top, DesRect.Right, DesRect.Top + CapInsetsRect.Top), Opacity, HighSpeed); // 左下 Self.DrawBitmap(Bitmap1, RectF(SrcRect.Left, SrcRect.Bottom - CapInsetsRect.Bottom, SrcRect.Left + CapInsetsRect.Left, SrcRect.Bottom), RectF(DesRect.Left, DesRect.Bottom - CapInsetsRect.Bottom, DesRect.Left + CapInsetsRect.Left, DesRect.Bottom), Opacity, HighSpeed); // 右下 Self.DrawBitmap(Bitmap1, RectF(SrcRect.Right - CapInsetsRect.Right, SrcRect.Bottom - CapInsetsRect.Bottom, SrcRect.Right, SrcRect.Bottom), RectF(DesRect.Right - CapInsetsRect.Right, DesRect.Bottom - CapInsetsRect.Bottom, DesRect.Right, DesRect.Bottom), Opacity, HighSpeed); // 左 Self.DrawBitmap(Bitmap1, RectF(SrcRect.Left, SrcRect.Top + CapInsetsRect.Top, SrcRect.Left + CapInsetsRect.Left, SrcRect.Bottom - CapInsetsRect.Bottom), RectF(DesRect.Left, DesRect.Top + CapInsetsRect.Top, DesRect.Left + CapInsetsRect.Left, DesRect.Bottom - CapInsetsRect.Bottom), Opacity, HighSpeed); // 上 Self.DrawBitmap(Bitmap1, RectF(SrcRect.Left + CapInsetsRect.Left, SrcRect.Top, SrcRect.Right - CapInsetsRect.Right, SrcRect.Top + CapInsetsRect.Top), RectF(DesRect.Left + CapInsetsRect.Left, DesRect.Top, DesRect.Right - CapInsetsRect.Right, DesRect.Top + CapInsetsRect.Top), Opacity, HighSpeed); // 右 Self.DrawBitmap(Bitmap1, RectF(SrcRect.Right - CapInsetsRect.Right, SrcRect.Top + CapInsetsRect.Top, SrcRect.Right, SrcRect.Bottom - CapInsetsRect.Bottom), RectF(DesRect.Right - CapInsetsRect.Right, DesRect.Top + CapInsetsRect.Top, DesRect.Right, DesRect.Bottom - CapInsetsRect.Bottom), Opacity, HighSpeed); // 下 Self.DrawBitmap(Bitmap1, RectF(SrcRect.Left + CapInsetsRect.Left, SrcRect.Bottom - CapInsetsRect.Bottom, SrcRect.Right - CapInsetsRect.Right, SrcRect.Bottom), RectF(DesRect.Left + CapInsetsRect.Left, DesRect.Bottom - CapInsetsRect.Bottom, DesRect.Right - CapInsetsRect.Right, DesRect.Bottom), Opacity, HighSpeed); // 中 Self.DrawBitmap(Bitmap1, RectF(SrcRect.Left + CapInsetsRect.Left, SrcRect.Top + CapInsetsRect.Top, SrcRect.Right - CapInsetsRect.Right, SrcRect.Bottom - CapInsetsRect.Bottom), RectF(DesRect.Left + CapInsetsRect.Left, DesRect.Top + CapInsetsRect.Top, DesRect.Right - CapInsetsRect.Right, DesRect.Bottom - CapInsetsRect.Bottom), Opacity, HighSpeed); end; end.
使用方法：
uses FMX.Graphics.Helper; procedure TForm1.PaintBox2Paint(Sender: TObject; Canvas: TCanvas); begin Canvas.DrawBitmapCapInsets(Image2.Bitmap, PaintBox2.LocalRect, RectF(17, 14, 24, 16)); end;
源码下载：
[原创]TestImageCapInsets_图片拉伸不变形.zip
参考资料：