绘制图形时遇到问题
本文关键字：问题 遇到 图形 绘制 | 更新日期: 2023-09-27 18:35:38
我在简单的表单上绘制图形时遇到问题。我的代码编译并运行，但预期的红框没有显示。
我在Visual Studio 2010中使用完整的.NET Framework 4。
出了什么问题，如何解决？
private void Form1_Load(object sender, EventArgs e)
{
System.Drawing.Graphics graphicsObj;
graphicsObj = this.CreateGraphics();
Pen myPen = new Pen(System.Drawing.Color.Red, 5);
Rectangle myRectangle = new Rectangle(20, 20, 250, 200);
graphicsObj.DrawRectangle(myPen, myRectangle);
}
编辑：工作但缓慢的代码
void BatteryPaint(object sender, EventArgs e)
{
TabPage page = (TabPage)sender;
if (!controlsSetup)
{
populateBatteryTab(page);
controlsSetup = true;
}
//Create the items
Rectangle busBar = new Rectangle();
Rectangle batPack = new Rectangle();
Rectangle pack1Outline = new Rectangle();
Rectangle pack2Outline = new Rectangle();
Rectangle pack3Outline = new Rectangle();
Rectangle pack4Outline = new Rectangle();
Color GreenZone = Color.FromArgb(150, 0, 255, 0);
Color YellowZone = Color.FromArgb(150, 255, 255, 0);
Color RedZone = Color.FromArgb(150, 255, 0, 0);
Color greyZone = Color.FromArgb(200, 200, 200, 200);
Graphics graphicControl = page.CreateGraphics();
SolidBrush busBarBrush = new SolidBrush(Color.Peru);
SolidBrush GreenBrush = new SolidBrush(GreenZone);
SolidBrush GreyBrush = new SolidBrush(greyZone);
Pen packPen = new Pen(Color.LightGray, (float)8);
Point busBarTop = new Point(page.Width / 64, page.Height / 32);
Point busBarBottom = new Point(busBarTop.X, busBarTop.Y + page.Height / 6);
//change the properties
//Bus Bar Top
busBar.Width = page.Width*153 / 640;
busBar.Height = page.Height / 64;
busBar.Location = busBarTop;
graphicControl.FillRectangle(busBarBrush, busBar);
//Bus Bar Bottom
busBar.Location = busBarBottom;
graphicControl.FillRectangle(busBarBrush, busBar);
//Pack 1
batPack.Width = page.Width / 20;
batPack.Height = (busBarBottom.Y + busBar.Height) - busBarTop.Y;
batPack.Location = new Point(busBarTop.X + page.Width / packSpacingMultiplier, busBarTop.Y);
pack1Outline.Width = batOutlineWidth;
graphicControl.FillRectangle(GreenBrush, batPack);
pack1Outline.Height = (3 * (Battery.Width + page.Width / batSpacingMultiplier) + page.Width / batSpacingMultiplier);
pack1Outline.Location = new Point(BatPack1.X - (page.Width / batSpacingMultiplier), BatPack1.Y - (page.Width / batSpacingMultiplier));
for(int numBats = 0; numBats < 30; numBats++)
{
Battery.Location = new Point(BatPack1.X + ((numBats % 10) * (Battery.Width + page.Width / batSpacingMultiplier)), BatPack1.Y + ((numBats / 10) * (Battery.Width + page.Width / batSpacingMultiplier)));
graphicControl.FillEllipse(new SolidBrush(BatteryZone(0.00)), Battery);
}
//Pack 2
batPack.Location = new Point(batPack.Location.X + batPack.Width + page.Width / packSpacingMultiplier, batPack.Location.Y);
graphicControl.FillRectangle(GreenBrush, batPack);
pack2Outline.Width = batOutlineWidth;
pack2Outline.Height = (3 * (Battery.Width + page.Width / batSpacingMultiplier) + page.Width / batSpacingMultiplier);
pack2Outline.Location = new Point(BatPack2.X - (page.Width / batSpacingMultiplier), BatPack2.Y - (page.Width / batSpacingMultiplier));
for(int numBats = 0; numBats < 30; numBats++)
{
Battery.Location = new Point(BatPack2.X + ((numBats % 10) * (Battery.Width + page.Width / batSpacingMultiplier)), BatPack2.Y + ((numBats / 10) * (Battery.Width + page.Width / batSpacingMultiplier)));
graphicControl.FillEllipse(new SolidBrush(BatteryZone(0.00)), Battery);
}
//Pack 3
batPack.Location = new Point(batPack.Location.X + batPack.Width + page.Width / packSpacingMultiplier, batPack.Location.Y);
graphicControl.FillRectangle(GreenBrush, batPack);
pack3Outline.Width = batOutlineWidth;
pack3Outline.Height = (3 * (Battery.Width + page.Width / batSpacingMultiplier) + page.Width / batSpacingMultiplier);
pack3Outline.Location = new Point(BatPack3.X - (page.Width / batSpacingMultiplier), BatPack3.Y - (page.Width / batSpacingMultiplier));
for(int numBats = 0; numBats < 30; numBats++)
{
Battery.Location = new Point(BatPack3.X + ((numBats % 10) * (Battery.Width + page.Width / batSpacingMultiplier)), BatPack3.Y + ((numBats / 10) * (Battery.Width + page.Width / batSpacingMultiplier)));
graphicControl.FillEllipse(new SolidBrush(BatteryZone(0.00)), Battery);
}
//Pack 4
batPack.Location = new Point(batPack.Location.X + batPack.Width + page.Width / packSpacingMultiplier, batPack.Location.Y);
graphicControl.FillRectangle(GreyBrush, batPack);
pack4Outline.Width = batOutlineWidth;
pack4Outline.Height = (3 * (Battery.Width + page.Width / batSpacingMultiplier) + page.Width / batSpacingMultiplier);
pack4Outline.Location = new Point(BatPack4.X - (page.Width / batSpacingMultiplier), BatPack4.Y - (page.Width / batSpacingMultiplier));
for(int numBats = 0; numBats < 30; numBats++)
{
Battery.Location = new Point(BatPack4.X + ((numBats % 10) * (Battery.Width + page.Width / batSpacingMultiplier)), BatPack4.Y + ((numBats / 10) * (Battery.Width + page.Width / batSpacingMultiplier)));
graphicControl.FillEllipse(new SolidBrush(BatteryZone(0.00)), Battery);
}
//add the controls
graphicControl.DrawRectangle(packPen, pack1Outline);
graphicControl.DrawRectangle(packPen, pack2Outline);
graphicControl.DrawRectangle(packPen, pack3Outline);
graphicControl.DrawRectangle(packPen, pack4Outline);
}
您不应该在 Load 事件中进行绘制，该事件甚至在首次显示表单之前就触发了。窗口在显示时会重新绘制，这会清除已绘制的图形。如果需要持久矩形，请改为处理 Paint 事件：
private void Form1_Paint(object sender, PaintEventArgs e)
{
System.Drawing.Graphics graphicsObj = e.Graphics;
Pen myPen = new Pen(System.Drawing.Color.Red, 5);
Rectangle myRectangle = new Rectangle(20, 20, 250, 200);
graphicsObj.DrawRectangle(myPen, myRectangle);
}
如果您不想要持久矩形（非常可疑，但仍有可能），请尝试处理Shown事件而不是Load事件。
如果显示的图形将频繁更新（例如在游戏中），请确保将DoubleBuffered设置为true并覆盖OnPaint而不是处理事件：
protected override void OnPaint(PaintEventArgs e)
{
Graphics g = e.Graphics;
Pen myPen = new Pen(Color.Red, 5);
g.DrawRectangle(myPen, 20, 20, 250, 200);
}