Jna Pointer to 32-bit JRE

Question

I use jna to call api increment functions in Java.

MagImageScalingCallback.java

package jna.extra; import com.sun.jna.Callback; import com.sun.jna.Pointer; import com.sun.jna.platform.win32.WinDef.HRGN; import com.sun.jna.platform.win32.WinDef.HWND; import com.sun.jna.platform.win32.WinDef.RECT; public interface MagImageScalingCallback extends Callback{ public Boolean MagImageScalingCallback(HWND hwnd, Pointer srcdata,MAGIMAGEHEADER srcheader, Pointer destdata,MAGIMAGEHEADER destheader,RECT source,RECT clipped,HRGN dirty); } 

MAGIMAGEHEADER.java

 package jna.extra; import java.util.Arrays; import java.util.List; import com.sun.jna.platform.win32.Guid.GUID; public class MAGIMAGEHEADER extends com.sun.jna.Structure { public int width; public int height; public GUID format; public int stride; public int offset; public int cbsize; public List getFieldOrder() { return Arrays.asList("width","height","format","stride","offset","cbsize"); } } 

Magnification.java

 package jna.extra; import com.sun.jna.Native; import com.sun.jna.platform.win32.WinDef.DWORD; import com.sun.jna.platform.win32.WinDef.HWND; import com.sun.jna.platform.win32.WinDef.RECT; import com.sun.jna.win32.StdCallLibrary; import com.sun.jna.win32.W32APIOptions; public interface Magnification extends StdCallLibrary { Magnification INSTANCE = (Magnification) Native.loadLibrary("magnification", Magnification.class, W32APIOptions.DEFAULT_OPTIONS); public Boolean MagInitialize(); public boolean MagSetWindowFilterList(HWND hwndMag, DWORD dword, int i, HWND[] excludeHWNDs); public boolean MagSetWindowSource(HWND hwndMag, RECT sourceRect); public void MagGetWindowFilterList(HWND hwndMag, DWORD dword, int i, HWND[] test); public boolean MagSetImageScalingCallback(HWND hwndMag,MagImageScalingCallback MagImageScalingCallback); public MagImageScalingCallback MagGetImageScalingCallback(HWND hwndMag); } 

WinGDIExtra.java

 package jna.extra; import com.sun.jna.platform.win32.WinDef.DWORD; import com.sun.jna.platform.win32.WinGDI; public interface WinGDIExtra extends WinGDI { public DWORD SRCCOPY = new DWORD(0x00CC0020); public DWORD SRCPAINT = new DWORD(0x00ee0086); public DWORD SRCAND = new DWORD(0x008800c6); public DWORD SRCINVERT = new DWORD(0x00660046); public DWORD SRCERASE = new DWORD(0x00440328); public DWORD NOTSRCCOPY = new DWORD(0x00330008); public DWORD NOTSRCERASE = new DWORD(0x001100a6); public DWORD MERGECOPY = new DWORD(0x00c000ca); public DWORD MERGEPAINT = new DWORD(0x00bb0226); public DWORD PATCOPY = new DWORD(0x00f00021); public DWORD PATPAINT = new DWORD(0x00fb0a09); public DWORD PATINVERT = new DWORD(0x005a0049); public DWORD DSTINVERT = new DWORD(0x00550009); public DWORD WHITENESS = new DWORD(0x00ff0062); public DWORD BLACKNESS = new DWORD(0x00000042); public DWORD CAPTUREBLT = new DWORD(0x00CC0020 | 0x40000000); public DWORD Black = new DWORD(0x00000000); public long WS_CHILD = 0x40000000L; public long WS_VISIBLE = 0x10000000L; public long MS_SHOWMAGNIFIEDCURSOR = 0x0001L; public long WS_EX_TOPMOST = 0x00000008L; public long WS_EX_LAYERED = 0x00080000; public long WS_EX_TRANSPARENT = 0x00000020L; public long WS_CLIPCHILDREN = 0x02000000L; public long MW_FILTERMODE_EXCLUDE = 0; } 

My code

 package jna.extra; import java.awt.image.BufferedImage; import java.io.File; import java.io.IOException; import javax.imageio.ImageIO; import com.sun.jna.platform.win32.Kernel32; import com.sun.jna.platform.win32.WinDef.DWORD; import com.sun.jna.platform.win32.WinDef.HRGN; import com.sun.jna.platform.win32.WinDef.RECT; import com.sun.jna.platform.win32.WinDef.HWND; import com.sun.jna.Native; import com.sun.jna.Pointer; import luz.winapi.jna.User32; public class screenSkip { public static void main(String[] args){ if(!Magnification.INSTANCE.MagInitialize()){ System.out.println("Cannot Intialize Magnification API"); System.exit(0); } RECT desktopRect= new RECT(); HWND desktop = User32.INSTANCE.GetDesktopWindow(); if(desktop==null){ System.out.println("Problem with Desktop"); System.exit(0); } if(!User32Extra.INSTANCE.GetWindowRect(desktop, desktopRect)){ System.err.println("Cannot get window rect"); System.exit(0); } HWND top = User32Extra.INSTANCE.CreateWindowEx(new DWORD(WinGDIExtra.WS_EX_TOPMOST | WinGDIExtra.WS_EX_LAYERED | WinGDIExtra.WS_EX_TRANSPARENT), "#32770", "Parent Window", new DWORD(WinGDIExtra.WS_CLIPCHILDREN), desktopRect.left, desktopRect.top, desktopRect.right-desktopRect.left, desktopRect.bottom-desktopRect.top, desktop, null, null, null); if(top==null){ System.out.println("Problem while creating Parent Window and the error is "+Native.getLastError()); System.exit(0); } HWND hwndMag=null; System.out.println(Native.getLastError()); hwndMag = User32Extra.INSTANCE.CreateWindowEx(null, "Magnifier", "MagWindow", new DWORD(WinGDIExtra.WS_CHILD | WinGDIExtra.MS_SHOWMAGNIFIEDCURSOR | WinGDIExtra.WS_VISIBLE), desktopRect.left, desktopRect.top, desktopRect.right-desktopRect.left, desktopRect.bottom-desktopRect.top, top, null, Kernel32.INSTANCE.GetModuleHandle(null), null); if(hwndMag==null){ System.err.println("Problem while creating Magnifier Window and the error is "+Native.getLastError()); System.exit(0); } RECT sourceRect= new RECT(); if(!User32Extra.INSTANCE.GetWindowRect(desktop, sourceRect)){ System.err.println("Cannot get window rect"); System.exit(0); } final BufferedImage image = new BufferedImage(1366, 768, BufferedImage.TYPE_INT_RGB); if(!Magnification.INSTANCE.MagSetImageScalingCallback(hwndMag,new MagImageScalingCallback() { public Boolean MagImageScalingCallback(HWND hwnd, Pointer srcdata, MAGIMAGEHEADER srcheader, Pointer destdata, MAGIMAGEHEADER destheader, RECT source, RECT clipped, HRGN dirty) { image.setRGB(0, 0, srcheader.width, srcheader.height, srcdata.getIntArray(0, srcheader.width * srcheader.height ), 0, srcheader.width); return true; } })){ System.err.println("Error occured while setting callback"); System.exit(0); } if (!Magnification.INSTANCE.MagSetWindowSource(hwndMag, sourceRect)) { System.err.println("Cannot copy"); System.exit(0); } try { ImageIO.write(image, "JPEG", new File("printed1.jpg")); } catch (IOException e) { e.printStackTrace(); } if (!Magnification.INSTANCE.MagSetWindowSource(hwndMag, sourceRect)) { System.err.println("Cannot copy"); System.exit(0); } } } 

If the MagSetWindowSource function MagSetWindowSource called, the MagImageScalingCallback function is MagImageScalingCallback .

The problem is that I run this code with jre7 (64-bit), everything works fine. But if I run the same code in jre7 (32 bit), I get the following error.

 #
 # A fatal error has been detected by the Java Runtime Environment:
 #
 # EXCEPTION_ACCESS_VIOLATION (0xc0000005) at pc = 0x10002a21, pid = 5552, tid = 4884
 #
 # JRE version: Java (TM) SE Runtime Environment (7.0_80-b15) (build 1.7.0_80-b15)
 # Java VM: Java HotSpot (TM) Client VM (24.80-b11 mixed mode, sharing windows-x86)
 # Problematic frame:
 # C [jna6797525900717560222.dll + 0x2a21]
 #
 # Failed to write core dump.  Minidumps are not enabled by default on client versions of Windows
 #
 # If you would like to submit a bug report, please visit:
 # http://bugreport.java.com/bugreport/crash.jsp
 # The crash happened outside the Java Virtual Machine in native code.
 # See problematic frame for where to report the bug.
 #

 Stack: [0x05c60000,0x05cb0000], sp = 0x05cae4d0, free space = 313k
 Native frames: (J = compiled Java code, j = interpreted, Vv = VM code, C = native code)
 C [jna6797525900717560222.dll + 0x2a21]
 j com.sun.jna.Pointer._getInt (J) I + 0
 j com.sun.jna.Pointer.getInt (J) I + 6
 j com.sun.jna.Pointer.getValue (JLjava / lang / Class; Ljava / lang / Object;) Ljava / lang / Object; +340
 j com.sun.jna.Structure.readField (Lcom / sun / jna / Structure $ StructField;) Ljava / lang / Object; +168
 j com.sun.jna.Structure.read () V + 82
 j com.sun.jna.CallbackReference $ DefaultCallbackProxy.convertArgument (Ljava / lang / Object; Ljava / lang / Class;) Ljava / lang / Object; +330
 j com.sun.jna.CallbackReference $ DefaultCallbackProxy.invokeCallback ([Ljava / lang / Object;) Ljava / lang / Object; +95
 j com.sun.jna.CallbackReference $ DefaultCallbackProxy.callback ([Ljava / lang / Object;) Ljava / lang / Object; +2
 v ~ StubRoutines :: call_stub
 V [jvm.dll + 0x1429aa]
 V [jvm.dll + 0x20743e]
 V [jvm.dll + 0x142a2d]
 V [jvm.dll + 0xcb7b2]
 V [jvm.dll + 0xcd5df]
 C [jna6797525900717560222.dll + 0x9dd2]
 C [jna6797525900717560222.dll + 0xa47f]
 C [jna6797525900717560222.dll + 0xc864]
 C [jna6797525900717560222.dll + 0xcdee]
 C 0x00b80012
 C [magnification.dll + 0x5434]
 C [magnification.dll + 0x5a2c]
 C [magnification.dll + 0x5f5d]
 C [magnification.dll + 0x612a]
 C [magnification.dll + 0x28ab]
 C [USER32.dll + 0x162fa]
 C [USER32.dll + 0x16d3a]
 C [USER32.dll + 0x1965e]
 C [USER32.dll + 0x196c5]
 C [magnification.dll + 0x22e2]
 C [jna6797525900717560222.dll + 0xcc77]
 C [jna6797525900717560222.dll + 0xc78a]
 C [jna6797525900717560222.dll + 0x4561]
 C [jna6797525900717560222.dll + 0x4d2e]
 j com.sun.jna.Function.invokeInt (I [Ljava / lang / Object;) I + 0
 j com.sun.jna.Function.invoke ([Ljava / lang / Object; Ljava / lang / Class; Z) Ljava / lang / Object; +315
 j com.sun.jna.Function.invoke (Ljava / lang / Class; [Ljava / lang / Object; Ljava / util / Map;) Ljava / lang / Object; +214
 j com.sun.jna.Library $ Handler.invoke (Ljava / lang / Object; Ljava / lang / reflect / Method; [Ljava / lang / Object;) Ljava / lang / Object; +341
 j com.sun.proxy. $ Proxy5.MagSetWindowSource (Lcom / sun / jna / platform / win32 / WinDef $ HWND; Lcom / sun / jna / platform / win32 / WinDef $ RECT;) Z + 20
 j org.redfire.screen.ScreenShare $ CaptureScreen.run () V + 674
 j java.lang.Thread.run () V + 11
 v ~ StubRoutines :: call_stub
 V [jvm.dll + 0x1429aa]
 V [jvm.dll + 0x20743e]
 V [jvm.dll + 0x142b75]
 V [jvm.dll + 0x142bd7]
 V [jvm.dll + 0xed5cf]
 V [jvm.dll + 0x163c4c]
 V [jvm.dll + 0x1646a7]
 V [jvm.dll + 0x1a92f9]
 C [msvcr100.dll + 0x5c556]
 C [msvcr100.dll + 0x5c600]
 C [kernel32.dll + 0x133aa]
 C [ntdll.dll + 0x39f72]
 C [ntdll.dll + 0x39f45]

 Java frames: (J = compiled Java code, j = interpreted, Vv = VM code)
 j com.sun.jna.Pointer._getInt (J) I + 0
 j com.sun.jna.Pointer.getInt (J) I + 6
 j com.sun.jna.Pointer.getValue (JLjava / lang / Class; Ljava / lang / Object;) Ljava / lang / Object; +340
 j com.sun.jna.Structure.readField (Lcom / sun / jna / Structure $ StructField;) Ljava / lang / Object; +168
 j com.sun.jna.Structure.read () V + 82
 j com.sun.jna.CallbackReference $ DefaultCallbackProxy.convertArgument (Ljava / lang / Object; Ljava / lang / Class;) Ljava / lang / Object; +330
 j com.sun.jna.CallbackReference $ DefaultCallbackProxy.invokeCallback ([Ljava / lang / Object;) Ljava / lang / Object; +95
 j com.sun.jna.CallbackReference $ DefaultCallbackProxy.callback ([Ljava / lang / Object;) Ljava / lang / Object; +2
 v ~ StubRoutines :: call_stub
 j com.sun.jna.Function.invokeInt (I [Ljava / lang / Object;) I + 0
 j com.sun.jna.Function.invoke ([Ljava / lang / Object; Ljava / lang / Class; Z) Ljava / lang / Object; +315
 j com.sun.jna.Function.invoke (Ljava / lang / Class; [Ljava / lang / Object; Ljava / util / Map;) Ljava / lang / Object; +214
 j com.sun.jna.Library $ Handler.invoke (Ljava / lang / Object; Ljava / lang / reflect / Method; [Ljava / lang / Object;) Ljava / lang / Object; +341
 j com.sun.proxy. $ Proxy5.MagSetWindowSource (Lcom / sun / jna / platform / win32 / WinDef $ HWND; Lcom / sun / jna / platform / win32 / WinDef $ RECT;) Z + 20
 j org.redfire.screen.ScreenShare $ CaptureScreen.run () V + 674
 j java.lang.Thread.run () V + 11
 v ~ StubRoutines :: call_stub

How to solve this problem? How can I do this work on a 32 bit JRE? Thank!

Answer 1

First, MagImageScalingCallback is defined as a WINAPI function, which means that you must define the callback as a child of StdCallCallback .

Secondly, the return type is a simple boolean (you should not use Boolean for this).

Thirdly, the callback parameters MAGIMAGEHEADER , not MAGIMAGEHEADER * , but RECT not RECT * , which means that they need to be passed by value; therefore, the callback declaration should be modified as follows:

I added a RectByValue class containing the following:

 import com.sun.jna.platform.win32.WinDef; import com.sun.jna.Structure; public class RectByValue extends WinDef.RECT implements Structure.ByValue {} 

I changed the MagImageScalingCallback class as follows:

 import com.sun.jna.win32.StdCallLibrary; public interface MagImageScalingCallback extends StdCallLibrary.StdCallCallback { public boolean MagImageScalingCallback(HWND hwnd, Pointer srcdata,MAGIMAGEHEADER.ByValue srcheader, Pointer destdata,MAGIMAGEHEADER.ByValue destheader,RectByValue source,RectByValue clipped,HRGN dirty); } 

You need to add ByValue support for MAGIMAGEHEADER ; and also use SIZE_T for the last element of the structure:

 import java.util.Arrays; import java.util.List; import com.sun.jna.platform.win32.Guid.GUID; import com.sun.jna.platform.win32.BaseTSD; import com.sun.jna.Pointer; import com.sun.jna.Structure; public class MAGIMAGEHEADER extends Structure { public int width; public int height; public GUID format; public int stride; public int offset; public BaseTSD.SIZE_T cbsize; public List getFieldOrder() { return Arrays.asList("width","height","format", "stride","offset","cbsize"); } public static class ByValue extends MAGIMAGEHEADER implements Structure.ByValue { public ByValue() {} public ByValue(MAGIMAGEHEADER magimageheader) { super (magimageheader.getPointer()); width = magimageheader.width; height = magimageheader.height; format = magimageheader.format; stride = magimageheader.stride; offset = magimageheader.offset; cbsize = magimageheader.cbsize; } public ByValue(Pointer memory) { super(memory); } } public MAGIMAGEHEADER(Pointer memory) { super(memory); read(); } public MAGIMAGEHEADER() { } } 

I resized the screen to fit my display on screenSkip , so it is new BufferedImage(2160, 1440... instead of 1366, 786 and changed the creator of the callback code to:

 if(!Magnification.INSTANCE.MagSetImageScalingCallback(hwndMag, new MagImageScalingCallback() { public boolean MagImageScalingCallback(HWND hwnd, Pointer srcdata, MAGIMAGEHEADER.ByValue srcheader, Pointer destdata, MAGIMAGEHEADER.ByValue destheader, RectByValue source, RectByValue clipped, HRGN dirty) { image.setRGB(0, 0, srcheader.width, srcheader.height, srcdata.getIntArray(0, srcheader.width * srcheader.height ), 0, srcheader.width); return true; } })){ System.err.println("Error occured while setting callback"); System.exit(0); } 

The end product of running this in 32-bit or 64-bit mode is a file called This is about as minimal as I think it will achieve what you want.

.... yes ... it gives me an empty image on 32-bit. This seems wrong.