我要尋找或試圖實現的算法得出盒陰影（如CSS 3 specifiction），它接受下列參數：CSS3樣箱陰影執行/算法
從哪裏開始。
我特地爲Firefox/Chrome的源代碼，看看我是否可以從那裏拉的實現，沒有這樣的運氣！
我已經看過成線性漸變的算法，一個盒子，它留下何種作品，除與圓角矩形的陰影空像素，這可能是由於邊緣的半徑畫他們。
我在.NET中使用GDI +這樣做。我的目標不是爲圖像創建陰影。我已經看到有關這方面的文章。我想爲使用GDI +繪製的形狀創建陰影。
任何幫助表示讚賞！
我編碼你來處理在其內部的控制，並增加了所要求的控制的Tag的陰影（外或內）一個DropShadowPanel。
正如您可以在圖像控件看得到他們的身影定義爲：
標籤：
文本框：陰影效果：5,5,5,10，＃000000，noinset
日曆：陰影效果：10,10,80,30，＃0000FF，noinset
PictureBox的左上角：陰影效果：-50,20,50,10，＃888888，noinset
圖片框左下：陰影效果：10,10,20,20，＃442200，插圖
PictureBox的右下：陰影效果：0,0,50,50，＃442200，noinset
下面是面板的代碼： （它使用中間附圖成的圖像繪製到控制GDI對象之前，不使所述形式爬行 - 這實際工作相當快）
using System;
using System.Collections.Generic;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Linq;
using System.Text;
using System.Windows.Forms;
namespace WindowsFormsApplication4
{
public class DropShadowPanel : Panel
{
protected override void OnControlAdded(ControlEventArgs e)
{
e.Control.Paint += new PaintEventHandler(Control_Paint);
base.OnControlAdded(e);
}
void Control_Paint(object sender, PaintEventArgs e)
{
CheckDrawInnerShadow(sender as Control, e.Graphics);
}
private void CheckDrawInnerShadow(Control sender, Graphics g)
{
var dropShadowStruct = GetDropShadowStruct(sender);
if (dropShadowStruct == null || !dropShadowStruct.Inset)
{
return;
}
DrawInsetShadow(sender as Control, g);
}
protected override void OnControlRemoved(ControlEventArgs e)
{
e.Control.Paint -= new PaintEventHandler(Control_Paint);
}
protected override void OnPaint(PaintEventArgs e)
{
base.OnPaint(e);
DrawShadow(Controls.OfType<Control>().Where(c => c.Tag != null && c.Tag.ToString().StartsWith("DropShadow")), e.Graphics);
}
void DrawInsetShadow(Control control, Graphics g)
{
var dropShadowStruct = GetDropShadowStruct(control);
var rInner = new Rectangle(Point.Empty, control.Size);
var img = new Bitmap(rInner.Width, rInner.Height, g);
var g2 = Graphics.FromImage(img);
g2.CompositingMode = CompositingMode.SourceCopy;
g2.FillRectangle(new SolidBrush(dropShadowStruct.Color), 0, 0, control.Width, control.Height);
rInner.Offset(dropShadowStruct.HShadow, dropShadowStruct.VShadow);
rInner.Inflate(dropShadowStruct.Blur, dropShadowStruct.Blur);
rInner.Inflate(-dropShadowStruct.Spread, -dropShadowStruct.Spread);
double blurSize = dropShadowStruct.Blur;
double blurStartSize = blurSize;
do
{
var transparency = blurSize/blurStartSize;
var color = Color.FromArgb(((int)(255 * (transparency * transparency))), dropShadowStruct.Color);
rInner.Inflate(-1,-1);
DrawRoundedRectangle(g2, rInner, (int)blurSize, Pens.Transparent, color);
blurSize--;
} while (blurSize > 0);
g.DrawImage(img, 0, 0);
g.Flush();
g2.Dispose();
img.Dispose();
}
void DrawShadow(IEnumerable<Control> controls, Graphics g)
{
foreach (var control in controls)
{
var dropShadowStruct = GetDropShadowStruct(control);
if (dropShadowStruct.Inset)
{
continue; // must be handled by the control itself
}
DrawOutsetShadow(g, dropShadowStruct, control);
}
}
// drawing the loop on an image because of speed
private void DrawOutsetShadow(Graphics g, dynamic dropShadowStruct, Control control)
{
var rOuter = control.Bounds;
var rInner = control.Bounds;
rInner.Offset(dropShadowStruct.HShadow, dropShadowStruct.VShadow);
rInner.Inflate(-dropShadowStruct.Blur, -dropShadowStruct.Blur);
rOuter.Inflate(dropShadowStruct.Spread, dropShadowStruct.Spread);
rOuter.Offset(dropShadowStruct.HShadow, dropShadowStruct.VShadow);
var originalOuter = rOuter;
var img = new Bitmap(originalOuter.Width, originalOuter.Height, g);
var g2 = Graphics.FromImage(img);
var currentBlur = 0;
do
{
var transparency = (rOuter.Height - rInner.Height)/(double) (dropShadowStruct.Blur*2 + dropShadowStruct.Spread*2);
var color = Color.FromArgb(((int)(255 * (transparency * transparency))), dropShadowStruct.Color);
var rOutput = rInner;
rOutput.Offset(-originalOuter.Left, -originalOuter.Top);
DrawRoundedRectangle(g2, rOutput, currentBlur, Pens.Transparent, color);
rInner.Inflate(1, 1);
currentBlur = (int) ((double) dropShadowStruct.Blur*(1 - (transparency*transparency)));
} while (rOuter.Contains(rInner));
g2.Flush();
g2.Dispose();
g.DrawImage(img, originalOuter);
img.Dispose();
}
private static dynamic GetDropShadowStruct(Control control)
{
if (control.Tag == null || !(control.Tag is string) || !control.Tag.ToString().StartsWith("DropShadow"))
return null;
string[] dropShadowParams = control.Tag.ToString().Split(':')[1].Split(',');
var dropShadowStruct = new
{
HShadow = Convert.ToInt32(dropShadowParams[0]),
VShadow = Convert.ToInt32(dropShadowParams[1]),
Blur = Convert.ToInt32(dropShadowParams[2]),
Spread = Convert.ToInt32(dropShadowParams[3]),
Color = ColorTranslator.FromHtml(dropShadowParams[4]),
Inset = dropShadowParams[5].ToLowerInvariant() == "inset"
};
return dropShadowStruct;
}
private void DrawRoundedRectangle(Graphics gfx, Rectangle bounds, int cornerRadius, Pen drawPen, Color fillColor)
{
int strokeOffset = Convert.ToInt32(Math.Ceiling(drawPen.Width));
bounds = Rectangle.Inflate(bounds, -strokeOffset, -strokeOffset);
var gfxPath = new GraphicsPath();
if (cornerRadius > 0)
{
gfxPath.AddArc(bounds.X, bounds.Y, cornerRadius, cornerRadius, 180, 90);
gfxPath.AddArc(bounds.X + bounds.Width - cornerRadius, bounds.Y, cornerRadius, cornerRadius, 270, 90);
gfxPath.AddArc(bounds.X + bounds.Width - cornerRadius, bounds.Y + bounds.Height - cornerRadius, cornerRadius,
cornerRadius, 0, 90);
gfxPath.AddArc(bounds.X, bounds.Y + bounds.Height - cornerRadius, cornerRadius, cornerRadius, 90, 90);
}
else
{
gfxPath.AddRectangle(bounds);
}
gfxPath.CloseAllFigures();
gfx.FillPath(new SolidBrush(fillColor), gfxPath);
if (drawPen != Pens.Transparent)
{
var pen = new Pen(drawPen.Color);
pen.EndCap = pen.StartCap = LineCap.Round;
gfx.DrawPath(pen, gfxPath);
}
}
}
}
代碼寫得很快，沒有太多的回顧，所以可能會有錯誤，尤其是如果你在控件上設置wring標籤）。
PS。您可能會注意到內部陰影對某些控件不起作用。這是因爲它們是Windows系統控件的包裝。面板本身無法克服這一點，但你可以這樣做：http://www.codeproject.com/Articles/4548/Generating-missing-Paint-event-for-TreeView-and-Li
*「...我的目的不是爲圖像創建陰影，我已經看到了有關這個的文章...」我也在尋找那些，並且發現很少，其中很不好，你能告訴我你在這個主題上找到了哪些文章嗎？ –
@UweKeim，我沒有在文章或實現方面找到太多東西，但是我修改了下面選擇的答案以適合我的需要。工作也很好。 – series0ne