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PolylineTo

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說明：
PolylineTo 函式可在指定的裝置環境代碼(Device Context)上繪製一條或多條直線

引用函式庫：
GDI32

適用系統：
Windows NT 3.1 或 Windows 95以上

函式原型：

Declare Function PolylineTo Lib "gdi32" Alias "PolylineTo" ( _
    ByVal hdc As Long, _
    ByVal lppt As POINTAPI, _
    ByVal cCount As Long _
    ) As Long



參數型態及說明：
hdc：Long 要繪製的裝置環境代碼(Device Context)
lppt：POINTAPI 直線的 POINT 座標結構陣列
cCount：Long lppt 陣列中要繪製直線的點的數量(會從第一個與第二個點之間繪製一條直線，其它依此類推)

回傳值：
Long 繪製成功的話，將會回傳非零的數值；若繪製失敗的話，則回傳 0

.NET Framework API：
System.Drawing.Graphics.DrawLines

VB範例：

檢視原始碼 Visual Basic
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'VB的宣告
Private Declare Function PolylineTo Lib "gdi32" ( _
	ByVal hdc As Long, _
	ByRef lppt As POINTAPI, _
	ByVal cCount As Long _
	) As Long
Private Declare Function ReleaseDC Lib "user32" ( _
	ByVal hwnd As Long, _
	ByVal hdc As Long _
	) As Long
Private Declare Function GetDC Lib "user32" ( _
	ByVal hwnd As Long _
	) As Long
 
Dim hdc As Long
 
'取得目前執行視窗的裝置環境代碼(Device Context)
hdc = GetDC(Form1.hwnd)
 
'設定POINTAPI陣列
Dim pts(0 To 2) As POINTAPI
pts(0).x = 10: pts(0).y = 20
pts(1).x = 50: pts(1).y = 40
pts(2).x = 110: pts(2).y = 130
 
Dim rtvl As Long
 
'在目前執行視窗上依pts陣列中的座標來產生線段
rtvl = PolylineTo(hdc, pts(0), UBound(pts) + 1)
 
Dim r As Long
 
'釋放目前執行視窗的裝置環境代碼(Device Context)
r = ReleaseDC(Form1.hwnd, hdc)

RB範例：

檢視原始碼 REALBasic
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'RB的宣告
Declare Function PolylineTo Lib "gdi32" ( _
	hdc As Integer, _
	lppt As Ptr, _
	cCount As Integer _
	) As Boolean
Declare Function ReleaseDC Lib "user32" ( _
	hwnd As Integer, _
	hdc As Integer _
	) As Integer
Declare Function GetDC Lib "user32" ( _
	hwnd As Integer _
	) As Integer
 
Dim hdc As Integer
 
'取得目前執行視窗的裝置環境代碼(Device Context)
hdc = GetDC(Window1.WinHWND)
 
Dim pts(3) As MemoryBlock
pts(0) = New MemoryBlock(8)
pts(0).Long(0) = 10
pts(0).Long(4) = 20
pts(1) = New MemoryBlock(8)
pts(1).Long(0) = 50
pts(1).Long(4) = 40
pts(2) = New MemoryBlock(8)
pts(2).Long(0) = 110
pts(2).Long(4) = 130
 
Dim rtvl As Boolean
 
'在目前執行視窗上的(0, 0)畫一個長高為100的矩形
rtvl = PolylineTo(hdc, pts(1), 1)
 
Dim r As Integer
 
'釋放目前執行視窗的裝置環境代碼(Device Context)
r = ReleaseDC(Window1.WinHWND, hdc)

VB.NET範例：

檢視原始碼 VB.NET
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'宣告一個POINTAPI
Public Structure POINTAPI
	Dim x As UInteger
	Dim y As UInteger
End Structure
 
'VB.NET的宣告
<DllImport("gdi32.dll")> _
Shared Function PolylineTo( _
	ByVal hdc As IntPtr, _
	ByVal lppt As POINTAPI(), _
	ByVal cCount As UInteger _
	) As Boolean
End Function
<DllImport("user32.dll")> _
Shared Function ReleaseDC( _
	ByVal hwnd As IntPtr, _
	ByVal hdc As IntPtr _
	) As UInteger
End Function
<DllImport("user32.dll")> _
Shared Function GetDC( _
	ByVal hwnd As IntPtr _
	) As IntPtr
End Function
 
Dim hdc As IntPtr
 
'取得目前執行視窗的裝置環境代碼(Device Context)
hdc = GetDC(Me.Handle)
 
'設定POINTAPI陣列
Dim pts(2) As POINTAPI
pts(0).x = 10 : pts(0).y = 20
pts(1).x = 50 : pts(1).y = 40
pts(2).x = 110 : pts(2).y = 130
 
Dim rtvl As Boolean
 
'在目前執行視窗上依pts陣列中的座標來產生線段
rtvl = PolylineTo(hdc, pts, pts.Length)
 
Dim r As Integer
 
'釋放目前執行視窗的裝置環境代碼(Device Context)
r = ReleaseDC(Me.Handle, hdc)

C#範例：

檢視原始碼 C#
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//宣告一個POINTAPI
public struct POINTAPI {
	public uint x;
	public uint y;
}
 
//C#的宣告
[DllImport("gdi32")]
public static extern bool PolylineTo(
	IntPtr hdc, 
	POINTAPI[] lppt, 
	uint cCount
	);
[DllImport("user32")]
public static extern uint ReleaseDC(
	IntPtr hwnd, 
	IntPtr hdc
	);
[DllImport("user32")]
public static extern IntPtr GetDC(
	IntPtr hwnd
	);
 
IntPtr hdc;
 
//取得目前執行視窗的裝置環境代碼(Device Context)
hdc = GetDC(this.Handle);
 
//設定POINTAPI陣列
POINTAPI[] pts = new POINTAPI[3];
pts[0].x = 10; pts[0].y = 20;
pts[1].x = 50; pts[1].y = 40;
pts[2].x = 110; pts[2].y = 130;
 
bool rtvl;
 
//在目前執行視窗上依pts陣列中的座標來產生線段
rtvl = PolylineTo(hdc, pts, (uint)pts.Length);
 
uint r;
 
//釋放目前執行視窗的裝置環境代碼(Device Context)
r = ReleaseDC(this.Handle, hdc);

註釋：
REALbasic 在呼叫 PolylineTo 函式時，單一點還能正常執行；但是多點的話，執行出來的結果就有點不正常。

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