可以拖动手柄改变曲线形状。
Conmajia 2012
Updated on Feb. 18, 2018
In Photoshop, there is a very powerful feature Curve Adjust, as shown in figure 1.
figure 1 Curve Adjust in Photoshop
You can adjust image parameters by adding, deleting or dragging nodes of the image curve.
Basically, such a curve is simple to implement:
- A curve is presented by a series of points which are called nodes
- Each node is an adjustable handle
- Mouse events handlers for each node
Detailed design procedure is omitted. The result is show in figure 2:
figure 2 Animated Example
Sample Codes
The Node list.
List<Point> points;
Deal with node handlers.
Rectangle getHandle(Point p)
{
Rectangle rect = new Rectangle(
p.X - 3,
p.Y - 3,
6,
6);
return rect;
}
Check for mouse position.
bool isHandle(Point p)
{
foreach (Point pt in points)
{
if (isInside(p, getHandle(pt)))
{
downIndex = points.IndexOf(pt);
downPoint = pt;
current = pt;
return true;
}
}
return false;
}
Draw handlers.
void drawHandle(Graphics g, Point p)
{
if (points.IndexOf(p) == downIndex)
g.FillRectangle(
Brushes.Black,
getHandle(p));
else
g.DrawRectangle(
Pens.Black,
getHandle(p));
}
Draw the curve.
void drawCurve(Graphics g)
{
g.DrawCurve(Pens.Black, points.ToArray());
}
Total sample source code: download
The End. \\(\\Box\\)