delphi - Delphi7: TBitmap.Canvas.Handle = 0 -

-

i facing problem long time, , have not found me solve it. use tbitmap receive data coming camera (stream) , save image disk. exception occurs. after several tests found flaw: handle property of tbitmap's canvas value 0. bypass problem, when detect value 0 in handle, restart application (destroy , recreate tbitmap did not work), error occurs frequently. has had problem this? doing wrong? welcome. thank you.

tbitmap internally uses tbitmapcanvas wrapper object tbitmap.canvas. if have access source (graphics.pas) should have look. chances 1 or more winapi gdi calls don't handle return value in case of error. gdi calls have slim chance of failing, it's of gamble leave out checking each , every returned value gain bit of performance, in cases of high load these may first indicators things go wrong anyway.

i suggest try use debug dcu's step through program using tbitmap.canvas, list gdi calls used make things work, code these operations checking returned values , handling errors correctly. should enable find out more going on when connection camera failing, , decrease of overhead have using tbitmap.


Comments

Post a Comment

Popular posts from this blog

android - getbluetoothservice() called with no bluetoothmanagercallback -

-
i getting getbluetoothservice() called no bluetoothmanagercallback error in android application. i have no idea causing or bluetooth manager callbacks. can give me idea of causing problem or start looking. by reading android source code, seems warning cannot about. source code shows if call bluetoothsocket#connect(); then call bluetoothadapter.getdefaultadapter().getbluetoothservice(null); the key here, null parameter passes in above line. due this, there no callback, , bluetoothsocket class throw out warning. since warning, not think need it. https://android.googlesource.com/platform/frameworks/base/+/master/core/java/android/bluetooth/bluetoothsocket.java line 306 https://android.googlesource.com/platform/frameworks/base/+/master/core/java/android/bluetooth/bluetoothadapter.java line 1610
Read more

sql - ASP.NET SqlDataSource, like on SelectCommand -

-
i'm working on asp.net. have sqldatasource query hardcoded on selectcommand: <asp:sqldatasource id="datasource1" runat="server" cancelselectonnullparameter="false" connectionstring="<%$ connectionstrings:s.properties.settings.connectionstring %>" selectcommand="select * [table] ([col1] case @col1_param when null col1 else @col1_param end) , ([col2] case @col2_param when null col2 else @col2_param end)" selectcommandtype="text"> <selectparameters> <asp:controlparameter controlid="textbox1" name="col1_param" propertyname="text" type="string" /> <asp:controlparameter controlid="textbox2" name="col2_param" propertyname="text" type="string" /> </selectparameters> what want if enter data on 1 textbox only, data display according textbox
Read more

ios - Undefined symbols for architecture armv7: "_OBJC_CLASS_$_SSZipArchive" -

-
i try using extractzipfile plugin @ this: https://github.com/phonegap/phonegap-plugins/tree/master/ios/extractzipfile but when compiler xcode 4.6.1 in sdk 6.1 throws error: undefined symbols architecture i386: "_objc_class_$_ssziparchive", referenced from: objc-class-ref in extractzipfileplugin.o ld: symbol(s) not found architecture i386 clang: error: linker command failed exit code 1 (use -v see invocation) i try issue @ here: undefined symbols architecture armv7 ssziparchive but shows error: /users/alienware/desktop/extractzipfile/ssziparchive/tests/ssziparchivetests.m:10:9: 'sentestingkit/sentestingkit.h' file not found i work phonegap , make app in ios, dump. update : try add ssziparchive.m compiler source , come new error: undefined symbols architecture i386: "_unzclose", referenced from: +[ssziparchive unzipfileatpath:todestination:overwrite:password:error:delegate:] in ssziparchive.o "_unzclosecurrentfil
Read more