我正在尝试确定桌面的工作区域，即使任务栏被隐藏。
我有两个矩形，一个是屏幕的边界，另一个是任务栏的边界。我需要从屏幕矩形中减去任务栏矩形，以确定桌面可用的工作区域。实际上，我想要的是Screen.WorkingArea，但当任务栏被隐藏时不应包括在内。
假设屏幕矩形是X,Y,W,H = 0,0,1680,1050，任务栏矩形是X,Y,W,H = 0,1010,1680,40。我需要从第一个矩形中减去第二个矩形，以确定工作区域为0,0,1680,1010。
任务栏可以位于屏幕的任何一个侧面，我知道一定有比确定任务栏位置并使用单独的代码行为每个可能的位置生成新的矩形更好的方法。
-------------------------
| rectangle 1 |
| |
| ------------- |
| |rectangle 2| |
| ------------- |
| |
| |
-------------------------
-------------------------
| |
| |
| ------------- |
| | hole | |
| ------------- |
| |
| |
-------------------------
这个区域可以分解成4个矩形：
-------------------------
| A |
| |
|-----------------------|
| B | hole | C |
|-----------------------|
| |
| D |
-------------------------
// returns the rectangles which are part of rect1 but not part of rect2
NSArray* rectSubtract(CGRect rect1, CGRect rect2)
{
if (CGRectIsEmpty(rect1)) {
return @[];
}
CGRect intersectedRect = CGRectIntersection(rect1, rect2);
// No intersection
if (CGRectIsEmpty(intersectedRect)) {
return @[[NSValue valueWithCGRect:rect1]];
}
NSMutableArray* results = [NSMutableArray new];
CGRect remainder;
CGRect subtractedArea;
subtractedArea = rectBetween(rect1, intersectedRect, &remainder, CGRectMaxYEdge);
if (!CGRectIsEmpty(subtractedArea)) {
[results addObject:[NSValue valueWithCGRect:subtractedArea]];
}
subtractedArea = rectBetween(remainder, intersectedRect, &remainder, CGRectMinYEdge);
if (!CGRectIsEmpty(subtractedArea)) {
[results addObject:[NSValue valueWithCGRect:subtractedArea]];
}
subtractedArea = rectBetween(remainder, intersectedRect, &remainder, CGRectMaxXEdge);
if (!CGRectIsEmpty(subtractedArea)) {
[results addObject:[NSValue valueWithCGRect:subtractedArea]];
}
subtractedArea = rectBetween(remainder, intersectedRect, &remainder, CGRectMinXEdge);
if (!CGRectIsEmpty(subtractedArea)) {
[results addObject:[NSValue valueWithCGRect:subtractedArea]];
}
return results;
}
// returns the area between rect1 and rect2 along the edge
CGRect rectBetween(CGRect rect1, CGRect rect2, CGRect* remainder, CGRectEdge edge)
{
CGRect intersectedRect = CGRectIntersection(rect1, rect2);
if (CGRectIsEmpty(intersectedRect)) {
return CGRectNull;
}
CGRect rect3;
float chopAmount = 0;
switch (edge) {
case CGRectMaxYEdge:
chopAmount = rect1.size.height - (intersectedRect.origin.y - rect1.origin.y);
if (chopAmount > rect1.size.height) { chopAmount = rect1.size.height; }
break;
case CGRectMinYEdge:
chopAmount = rect1.size.height - (CGRectGetMaxY(rect1) - CGRectGetMaxY(intersectedRect));
if (chopAmount > rect1.size.height) { chopAmount = rect1.size.height; }
break;
case CGRectMaxXEdge:
chopAmount = rect1.size.width - (intersectedRect.origin.x - rect1.origin.x);
if (chopAmount > rect1.size.width) { chopAmount = rect1.size.width; }
break;
case CGRectMinXEdge:
chopAmount = rect1.size.width - (CGRectGetMaxX(rect1) - CGRectGetMaxX(intersectedRect));
if (chopAmount > rect1.size.width) { chopAmount = rect1.size.width; }
break;
default:
break;
}
CGRectDivide(rect1, remainder, &rect3, chopAmount, edge);
return rect3;
}
这是一个快速的、延迟执行的、易于理解的、跨平台的，并且可以轻松移植到其他语言的C#解决方案。
编辑：修正(subtrahend.IsEmpty)的情况，使代码不返回零面积的矩形。请查看评论以获取返回相邻矩形的方案。
//-------------------------
//| A |
//|-----------------------|
//| B | hole | C |
//|-----------------------|
//| D |
//-------------------------
public static IEnumerable<Rectangle> Subtract(this
Rectangle minuend,
Rectangle subtrahend)
{
subtrahend.Intersect(minuend);
//if (subtrahend.IsEmpty)
//if (subtrahend.Size.IsEmpty)
if ((subtrahend.Width | subtrahend.Height) == 0)
{
yield return minuend;
yield break;
}
//A
var heightA = subtrahend.Top - minuend.Top;
if (heightA > 0)
yield return new Rectangle(
minuend.Left,
minuend.Top,
minuend.Width,
heightA);
//B
var widthB = subtrahend.Left - minuend.Left;
if (widthB > 0)
yield return new Rectangle(
minuend.Left,
subtrahend.Top,
widthB,
subtrahend.Height);
//C
var widthC = minuend.Right - subtrahend.Right;
if (widthC > 0)
yield return new Rectangle(
subtrahend.Right,
subtrahend.Top,
widthC,
subtrahend.Height);
//D
var heightD = minuend.Bottom - subtrahend.Bottom;
if (heightD > 0)
yield return new Rectangle(
minuend.Left,
subtrahend.Bottom,
minuend.Width,
heightD);
}
http://msdn.microsoft.com/en-us/library/system.drawing.region_methods.aspx
这是一种简单的扩展，用于从彼此之间减去矩形。
public static Rectangle[] Subtract(this Rectangle source, Rectangle[] subtractions)
{
Region tmp = new Region(source);
foreach (var sub in subtractions)
{
tmp.Xor(sub);
}
Region src = new Region(source);
src.Intersect(tmp);
return src.GetRegionScans(new Matrix()).Select(Rectangle.Ceiling).ToArray();
}
除非矩形的三边重合，否则从一个矩形中减去另一个矩形将得到一个不是矩形的形状，因此“减去矩形”的一般解决方案并没有太多意义。
三边重合的解决方案：
给定矩形（Ax，Ay，Aw，Ah）和（Bx，By，Bw，Bh）：
（max（Ax，Bx），max（Ay，By），min（Ax + Aw，Bx + Bw）- max（Ax，Bx），min（Ay + Ah，By + Bh）- max（Ay，By）
已编辑。
正如Hai Feng Kao所说，减法的结果可以看作是一个List<Rect>
以下是C#的实现：
public static List<Rect> Subtract(this Rect rect, Rect subtracted)
{
if (rect.HasNoArea())
{
return _emptyList;
}
if (rect.Equals(subtracted))
{
return new List<Rect>{new Rect(0, 0, 0, 0)};
}
Rect intersectedRect = rect;
intersectedRect.Intersect(subtracted);
if (intersectedRect.HasNoArea())
{
return new List<Rect> { rect };
}
List<Rect> results = new List<Rect>();
var topRect = GetTopRect(rect, subtracted);
if (!topRect.HasNoArea())
{
results.Add(topRect);
}
var leftRect = GetLeftRect(rect, subtracted);
if (!leftRect.HasNoArea())
{
results.Add(leftRect);
}
var rightRect = GetRightRect(rect, subtracted);
if (!rightRect.HasNoArea())
{
results.Add(rightRect);
}
var bottomRect = GetBottomRect(rect, subtracted);
if (!bottomRect.HasNoArea())
{
results.Add(bottomRect);
}
return results;
}
public static bool HasNoArea(this Rect rect)
{
return rect.Height < tolerance || rect.Width < tolerance;
}
private static Rect GetTopRect(Rect rect, Rect subtracted)
{
return new Rect(rect.Left, rect.Top, rect.Width, Math.Max(subtracted.Top, 0));
}
private static Rect GetRightRect(Rect rect, Rect subtracted)
{
return new Rect(subtracted.Right, subtracted.Top, Math.Max(rect.Right - subtracted.Right, 0), subtracted.Height);
}
private static Rect GetLeftRect(Rect rect, Rect subtracted)
{
return new Rect(rect.Left, subtracted.Top, Math.Max(subtracted.Left - rect.Left, 0), subtracted.Height);
}
private static Rect GetBottomRect(Rect rect, Rect subtracted)
{
return new Rect(rect.Left, subtracted.Bottom, rect.Width, Math.Max(rect.Height - subtracted.Bottom, 0));
}
Rect 是一个 struct，因此它是按值复制的。
公差可以是任何足够小的值（如10^-6）。public Rectangle[] Subtract(Rectangle[] subtractions)
{// space to chop = this panel
Region src = new Region(Bounds);
foreach (var sub in subtractions)
{
Region tmp = src.Clone();
tmp.Xor(sub);
src.Intersect(tmp);
}
return src.GetRegionScans(new Matrix()).Select(Rectangle.Ceiling).ToArray();
}
Rect CalcWorkArea(Rect scrn, Rect tbar)
{
Rect work;
work.X = (tbar.X + tbar.W) % scrn.W;
work.Y = (tbar.Y + tbar.H) % scrn.H;
work.W = work.X + scrn.W - (tbar.W % scrn.W);
work.H = work.Y + scrn.H - (tbar.H % scrn.H);
return work;
}
我猜我对您试图推导什么感到困惑。.NET将桌面的当前工作区报告为显示器分辨率减去任务栏所占用的空间。
确定屏幕的工作区已经在.NET中公开（包括任务栏停靠在顶部或左侧时的移位X/Y坐标）。
// set the coordinate to the upper-left of the screen
Rectangle r = Screen.GetWorkingArea(new Point(0, 0));
// the resulting rectangle will show the deviation in X/Y
// and also the dimensions of the desktop (minus the Taskbar)
MessageBox.Show
(
r.ToString()
);