canvas does not allow drawing |
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答題得分者是：anpino
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paul67
一般會員   發表：20 回覆：18 積分：7 註冊：2003-03-17 發送簡訊給我 |
請問各位前輩..
弟目前寫了一段由Server端傳圖到client端做遠端視訊，但連線連個一天時卻會發生 canvas does not allow drawing的錯誤訊息。請問什麼原因會導致這個錯
誤出現呢。。以下是我網路部分程式碼
try{
if (AThread->Connection->Connected()){
if(APClosed){
szCommand = AThread->Connection->ReadInteger(true);
AThread->Connection->WriteInteger(-100,true);
return;
} szCommand = AThread->Connection->ReadInteger(true);
AnsiString split_Num = IntToStr(szCommand).SubString(1,1);
Graphics::TBitmap *bmp_Source bmp_Source = new Graphics::TBitmap;
TMemoryStream *msBuf = new TMemoryStream;
TJPEGImage *jpeg = new TJPEGImage; //若該頻道沒有接Camera則不傳送
/*if(!is_Transfer[NetCHCount]){
AThread->Connection->WriteInteger(-1,true);
delete msBuf;
msBuf = NULL;
delete jpeg;
jpeg = NULL;
delete bmp_Source;
bmp_Source = NULL; AThread->Connection->Tag ;
if (AThread->Connection->Tag >= 16)
AThread->Connection->Tag = 0; return;
} */
AThread->Connection->Tag = NetCHCount;
//NetCHCount = CHNumber[AThread->Connection->Tag]; switch(AThread->Connection->Tag)
{
case 0:
bmp_Source->Assign(NetBmp1);
break;
case 1:
bmp_Source->Assign(NetBmp2);
break;
case 2:
bmp_Source->Assign(NetBmp3);
break;
case 3:
bmp_Source->Assign(NetBmp4);
break;
case 4:
bmp_Source->Assign(NetBmp5);
break;
case 5:
bmp_Source->Assign(NetBmp6);
break;
case 6:
bmp_Source->Assign(NetBmp7);
break;
case 7:
bmp_Source->Assign(NetBmp8);
break;
case 8:
bmp_Source->Assign(NetBmp9);
break;
case 9:
bmp_Source->Assign(NetBmp10);
break;
case 10:
bmp_Source->Assign(NetBmp11);
break;
case 11:
bmp_Source->Assign(NetBmp12);
break;
case 12:
bmp_Source->Assign(NetBmp13);
break;
case 13:
bmp_Source->Assign(NetBmp14);
break;
case 14:
bmp_Source->Assign(NetBmp15);
break;
case 15:
bmp_Source->Assign(NetBmp16);
break;
} jpeg->Assign(bmp_Source);
jpeg->CompressionQuality = 72;
jpeg->Compress(); jpeg->SaveToStream(msBuf);
delete jpeg;
jpeg = NULL;
delete bmp_Source;
bmp_Source = NULL; if (split_Num == "1"){
if (AThread->Connection->Tag != StrToInt(IntToStr(szCommand).SubString(2,3))){
AThread->Connection->WriteInteger(-1,true);
delete msBuf;
msBuf = NULL;
return;
}
}
else if (split_Num == "4"){
CH1 = ((StrToInt(IntToStr(szCommand).SubString(2,3)) 0) % 16);
CH2 = ((StrToInt(IntToStr(szCommand).SubString(2,3)) 1) % 16);
CH3 = ((StrToInt(IntToStr(szCommand).SubString(2,3)) 2) % 16);
CH4 = ((StrToInt(IntToStr(szCommand).SubString(2,3)) 3) % 16);
if (CH1 != AThread->Connection->Tag && CH2 != AThread->Connection->Tag && CH3 != AThread->Connection->Tag && CH4 != AThread->Connection->Tag){
AThread->Connection->WriteInteger(-1,true);
delete msBuf;
msBuf = NULL;
return;
}
}
else if (split_Num == "9"){
CH1 = ((StrToInt(IntToStr(szCommand).SubString(2,3)) 0) % 16);
CH2 = ((StrToInt(IntToStr(szCommand).SubString(2,3)) 1) % 16);
CH3 = ((StrToInt(IntToStr(szCommand).SubString(2,3)) 2) % 16);
CH4 = ((StrToInt(IntToStr(szCommand).SubString(2,3)) 3) % 16);
CH5 = ((StrToInt(IntToStr(szCommand).SubString(2,3)) 4) % 16);
CH6 = ((StrToInt(IntToStr(szCommand).SubString(2,3)) 5) % 16);
CH7 = ((StrToInt(IntToStr(szCommand).SubString(2,3)) 6) % 16);
CH8 = ((StrToInt(IntToStr(szCommand).SubString(2,3)) 7) % 16);
CH9 = ((StrToInt(IntToStr(szCommand).SubString(2,3)) 8) % 16); if (CH1 != AThread->Connection->Tag && CH2 != AThread->Connection->Tag && CH3 != AThread->Connection->Tag && CH4 != AThread->Connection->Tag && CH5!=AThread->Connection->Tag
&& CH6!=AThread->Connection->Tag && CH7!=AThread->Connection->Tag && CH8!= AThread->Connection->Tag && CH9!= AThread->Connection->Tag)
{
AThread->Connection->WriteInteger(-1,true);
delete msBuf;
msBuf = NULL;
return;
} } //jpeg->Assign(bmp_Dest); if (szCommand != 0){
msBuf->Position=0;
AThread->Connection->WriteInteger(AThread->Connection->Tag,true);
AThread->Connection->WriteStream(msBuf,true,true); // transfer data stream to internet
}
else{
delete msBuf;
msBuf = NULL;
AThread->Connection->Disconnect();
return;
} delete msBuf;
msBuf = NULL; } }catch(const EIdConnClosedGracefully &eCloseErr)
{
delete msBuf;
msBuf = NULL;
AThread->Connection->Disconnect();
return;
} 發表人 - taishyang 於 2004/01/05 20:51:52
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海星
高階會員  發表：41 回覆：217 積分：106 註冊：2003-01-09 發送簡訊給我 |
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jason_cyl329
高階會員 發表：123 回覆：155 積分：105 註冊：2003-05-26 發送簡訊給我 |
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anpino
版主 發表：31 回覆：477 積分：231 註冊：2003-01-02 發送簡訊給我 |
canvas does not allow drawing 的錯誤會在兩個以上的threads同時讓一個Canvas執行繪圖動作時發生, 例如2個threads同時呼叫Image1->Canvas->Ellipse(). Draw()...等等繪圖函式。 請檢查所有的Canvas, 並讓繪圖動作只由一個thread 來做。
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paul67
一般會員 發表：20 回覆：18 積分：7 註冊：2003-03-17 發送簡訊給我 |
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anpino
版主 發表：31 回覆：477 積分：231 註冊：2003-01-02 發送簡訊給我 |
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paul67
一般會員 發表：20 回覆：18 積分：7 註冊：2003-03-17 發送簡訊給我 |
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anpino
版主 發表：31 回覆：477 積分：231 註冊：2003-01-02 發送簡訊給我 |
發表時間：2004-01-05 20:42:49
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系統時間：2024-11-22 20:26:13
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