MdispOverlay
This program shows how to display an image while creating text and graphics annotations on top of it using AIL graphic functions and windows GDI drawing under Windows. If the target system supports grabbing, the annotations are done on top of live video.
Language: C++
Functions used: MbufClear, MappAlloc, MappControl, MappFree, MbufAllocColor, MbufControl, MbufFree, MbufRestore, MbufInquire, MdigAlloc, MdigFree, MdigGrabContinuous, MdigHalt, MdigInquire, MdispAlloc, MdispControl, MdispFree, MdispInquire, MdispSelect, MgraControl, MgraText, MsysAlloc, MsysFree, MsysInquire
Categories: Overview, General, Industries, Applications, Modules, Buffer, Display, Graphics, Digitizer, What's New, Older
///////////////////////////////////////////////////////////////////////////////
// Aurora Imaging Library
// Filename: MDispOverlay.cpp
//
// Description: This program shows how to display an image while creating
// textand graphics annotations on top of it using AIL
// graphic functionsand windows GDI drawing under Windows
// or cairo drawing under Linux.
// If the target system supports grabbing, the annotations
// are done on top of a continuous grab.
//
// (C) 1992-2026 Zebra Technologies Corp. and/or its affiliates
// All Rights Reserved
///////////////////////////////////////////////////////////////////////////////
#include <AIL.h>
#if M_AIL_USE_WINDOWS
#include <windows.h>
#else
#include <stdlib.h>
#include <cairo.h>
#endif
// Target image.
#define IMAGE_FILE M_IMAGE_PATH AIL_TEXT("Board.mim")
// Title for the display window.
#define WINDOW_TITLE AIL_TEXT("Custom Title")
// Overlay drawing function prototype.
void OverlayDraw(AIL_ID Display);
int MosMain(void)
{
AIL_ID AilApplication, // Application identifier.
AilSystem, // System identifier.
AilDisplay, // Display identifier.
AilDigitizer=0, // Digitizer identifier.
AilImage; // Image identifier.
// Allocate defaults
MappAllocDefault(M_DEFAULT, &AilApplication, &AilSystem, &AilDisplay, M_NULL, M_NULL);
// If the system have a digitizer, use it.
if (MsysInquire(AilSystem, M_DIGITIZER_NUM, M_NULL))
{
MdigAlloc(AilSystem, M_DEFAULT, AIL_TEXT("M_DEFAULT"), M_DEFAULT, &AilDigitizer);
MbufAllocColor(AilSystem,
MdigInquire(AilDigitizer,M_SIZE_BAND,M_NULL),
MdigInquire(AilDigitizer,M_SIZE_X,M_NULL),
MdigInquire(AilDigitizer,M_SIZE_Y,M_NULL),
8+M_UNSIGNED,
M_IMAGE+M_DISP+M_PROC+M_GRAB,
&AilImage);
MbufClear(AilImage, 0);
}
else
{
// Restore a static image.
MbufRestore(IMAGE_FILE, AilSystem, &AilImage);
}
// Change display window title.
MdispControl(AilDisplay, M_TITLE, WINDOW_TITLE);
// Display the image buffer.
MdispSelect(AilDisplay, AilImage);
// Draw text and graphics annotations in the display overlay.
OverlayDraw(AilDisplay);
// If the system supports it, grab continuously in the displayed image.
if (AilDigitizer)
MdigGrabContinuous(AilDigitizer, AilImage);
// Pause to show the image.
MosPrintf(AIL_TEXT("\nOVERLAY ANNOTATIONS:\n"));
MosPrintf(AIL_TEXT("--------------------\n\n"));
MosPrintf(AIL_TEXT("Displaying an image with overlay annotations.\n"));
MosPrintf(AIL_TEXT("Press any key to continue.\n\n"));
MosGetch();
// Stop the continuous grab and free digitizer if needed.
if (AilDigitizer)
{
MdigHalt(AilDigitizer);
MdigFree(AilDigitizer);
// Pause to show the result.
MosPrintf(AIL_TEXT("Displaying the last grabbed image.\n"));
MosPrintf(AIL_TEXT("Press any key to end.\n\n"));
MosGetch();
}
// Free image.
MbufFree(AilImage);
// Free default allocations.
MappFreeDefault(AilApplication, AilSystem, AilDisplay, M_NULL, M_NULL);
return 0;
}
// ---------------------------------------------------------------
// Name: OverlayDraw
// Synopsis: This function draws annotations in the display overlay.
void OverlayDraw(AIL_ID AilDisplay)
{
AIL_ID AilOverlayImage;
AIL_INT ImageWidth, ImageHeight;
int Count;
AIL_TEXT_CHAR chText[80];
// Prepare overlay buffer.
//*************************
// Enable the display of overlay annotations.
MdispControl(AilDisplay, M_OVERLAY, M_ENABLE);
// Inquire the overlay buffer associated with the display.
MdispInquire(AilDisplay, M_OVERLAY_ID, &AilOverlayImage);
// Clear the overlay to transparent.
MdispControl(AilDisplay, M_OVERLAY_CLEAR, M_DEFAULT);
// Disable the overlay display update to accelerate annotations.
MdispControl(AilDisplay, M_OVERLAY_SHOW, M_DISABLE);
// Inquire overlay size.
ImageWidth = MbufInquire(AilOverlayImage, M_SIZE_X, M_NULL);
ImageHeight = MbufInquire(AilOverlayImage, M_SIZE_Y, M_NULL);
// Draw overlay annotations.
//*******************************
// Set the graphic text background to transparent.
MgraControl(M_DEFAULT, M_BACKGROUND_MODE, M_TRANSPARENT);
// Print a white string in the overlay image buffer.
MgraControl(M_DEFAULT, M_COLOR, M_COLOR_WHITE);
MgraText(M_DEFAULT, AilOverlayImage, ImageWidth/9, ImageHeight/5,
AIL_TEXT(" -------------------- "));
MgraText(M_DEFAULT, AilOverlayImage, ImageWidth/9, ImageHeight/5+25,
AIL_TEXT(" - overlay Text - "));
MgraText(M_DEFAULT, AilOverlayImage, ImageWidth/9, ImageHeight/5+50,
AIL_TEXT(" -------------------- "));
// Print a green string in the overlay image buffer.
MgraControl(M_DEFAULT, M_COLOR, M_COLOR_GREEN);
MgraText(M_DEFAULT, AilOverlayImage, ImageWidth*11/18, ImageHeight/5,
AIL_TEXT(" ---------------------"));
MgraText(M_DEFAULT, AilOverlayImage, ImageWidth*11/18, ImageHeight/5+25,
AIL_TEXT(" - overlay Text - "));
MgraText(M_DEFAULT, AilOverlayImage, ImageWidth*11/18, ImageHeight/5+50,
AIL_TEXT(" ---------------------"));
// Re-enable the overlay display after all annotations are done.
MdispControl(AilDisplay, M_OVERLAY_SHOW, M_ENABLE);
// Draw GDI/Cairo color overlay annotation
//***********************************
// Disable error printing for the inquire might not be supported
MappControl(M_DEFAULT, M_ERROR, M_PRINT_DISABLE);
#if M_AIL_USE_WINDOWS
HDC hCustomDC;
HGDIOBJ hpen, hpenOld;
// Create a device context to draw in the overlay buffer with GDI.
MbufControl(AilOverlayImage, M_DC_ALLOC, M_DEFAULT);
// Inquire the device context.
hCustomDC = ((HDC)MbufInquire(AilOverlayImage, M_DC_HANDLE, M_NULL));
// Re-enable error printing
MappControl(M_DEFAULT, M_ERROR, M_PRINT_ENABLE);
// Perform operation if GDI drawing is supported.
if (hCustomDC)
{
POINT Hor[2];
POINT Ver[2];
SIZE TxtSz;
RECT Txt;
// Draw a blue cross.
hpen=CreatePen(PS_SOLID, 1, RGB(0, 0, 255));
hpenOld = SelectObject(hCustomDC, hpen);
Hor[0].x = (AIL_INT32)0;
Hor[0].y = (AIL_INT32)(ImageHeight/2);
Hor[1].x = (AIL_INT32)ImageWidth;
Hor[1].y = (AIL_INT32)(ImageHeight/2);
Polyline(hCustomDC, Hor,2);
Ver[0].x = (AIL_INT32)(ImageWidth/2);
Ver[0].y = (AIL_INT32)0;
Ver[1].x = (AIL_INT32)(ImageWidth/2);
Ver[1].y = (AIL_INT32)ImageHeight;
Polyline(hCustomDC, Ver,2);
SelectObject(hCustomDC, hpenOld);
DeleteObject(hpen);
// Prepare transparent text annotations.
SetBkMode(hCustomDC, TRANSPARENT);
MosStrcpy(chText, 80, AIL_TEXT("GDI Overlay Text"));
Count = (int) MosStrlen(chText);
GetTextExtentPoint(hCustomDC, chText, Count, &TxtSz);
// Write red text.
Txt.left = (AIL_INT32)(ImageWidth*3/18);
Txt.top = (AIL_INT32)(ImageHeight*17/24);
Txt.right = (AIL_INT32)(Txt.left + TxtSz.cx);
Txt.bottom = (AIL_INT32)(Txt.top + TxtSz.cy);
SetTextColor(hCustomDC,RGB(255, 0, 0));
DrawText(hCustomDC, chText, Count, &Txt, DT_RIGHT);
// Write yellow text.
Txt.left = (AIL_INT32)ImageWidth*12/18;
Txt.top = (AIL_INT32)ImageHeight*17/24;
Txt.right = (AIL_INT32)(Txt.left + TxtSz.cx);
Txt.bottom = (AIL_INT32)(Txt.top + TxtSz.cy);
SetTextColor(hCustomDC, RGB(255, 255, 0));
DrawText(hCustomDC, chText, Count, &Txt, DT_RIGHT);
// Delete device context.
MbufControl(AilOverlayImage, M_DC_FREE, M_DEFAULT);
// Signal that the overlay buffer was modified.
MbufControl(AilOverlayImage, M_MODIFIED, M_DEFAULT);
}
#else
// Create a cairo surface to draw in the overlay buffer.
MbufControl(AilOverlayImage, M_SURFACE_ALLOC, M_COMPENSATION_ENABLE);
// Inquire the cairo surface.
cairo_surface_t * surface = ((cairo_surface_t *)MbufInquire(AilOverlayImage, M_SURFACE_HANDLE, M_NULL));
if(surface)
{
cairo_t *cr;
cr = cairo_create (surface);
cairo_set_source_rgb (cr, 0, 0, 1);
// Draw a blue cross in the overlay buffer.
cairo_move_to (cr, 0, ImageHeight/2);
cairo_line_to (cr, ImageWidth, ImageHeight/2);
cairo_stroke (cr);
cairo_move_to (cr, ImageWidth/2, 0);
cairo_line_to (cr, ImageWidth/2, ImageHeight);
cairo_stroke (cr);
// Write Red text in the overlay buffer.
MosStrcpy(chText, 80, "Cairo Overlay Text ");
cairo_select_font_face (cr, "monospace", CAIRO_FONT_SLANT_NORMAL, CAIRO_FONT_WEIGHT_NORMAL);
cairo_set_source_rgb (cr, 1, 0, 0);
cairo_set_font_size(cr, 13);
cairo_move_to(cr, ImageWidth*3/18, ImageHeight*4/6);
cairo_show_text(cr, chText);
// Write Yellow text in the overlay buffer.
cairo_set_source_rgb (cr, 1, 1, 0);
cairo_set_font_size(cr, 13);
cairo_move_to(cr, ImageWidth*12/18,ImageHeight*4/6);
cairo_show_text(cr, chText);
cairo_surface_flush(surface);
cairo_destroy(cr);
// Delete device context.
MbufControl(AilOverlayImage, M_SURFACE_FREE, M_DEFAULT);
// Signal that the overlay buffer was modified.
MbufControl(AilOverlayImage, M_MODIFIED, M_DEFAULT);
}
#endif
}