[directfb-users] Want to implement a surface larger than the display window and pan/copy contents - Follow up

[myke predko]

Heya,

Hi Folks,
As it says in the subject line, I would like to create an DirectFB
1. The ability to use the Draw functions in an area outside the viewable
area (ie invisible to the user).
2. Pan the data in the area outside the viewable area into (and out of)
the viewable area.
3. Copy data from one part of the surface to another, to provide
temporary saving (I realize that I could use the "Dump" API for this,
create a png and when I want to restore it, load it back in but this
seems somewhat inefficient) as well as a provide a very fast (or fade in)
transition between images.
Can anybody point me to any references or example code explaining how
this could be done? I'm using the basic DirectFB package (ie no
QT/Qtopia) to try and keep the code footprint as small as possible.
Thanx - I really appreciate any suggestions that people would have for
me.
myke

I wanted to follow up and say that I believe that I have solved all my
problems.

What I was missing was an understanding of how “surfaces” work in DirectFB;
they provide the ability of drawing off screen, bring data into the viewable
area and provide the ability to temporarily save data off screen.

To demonstrate this operation, I created the application below so hopefully
somebody else new to working with DirectFB and wanting similar capabilities
will have a place to start. I would also appreciate any of the old hands at
DirectFB reviewing the code below and commenting/suggesting on where I have
done things wrong/could be done better or more efficiently.

My application runs on a Freescale i.MX233, which is an ARM without video
hardware acceleration running Linux 2.6.31. The display is 480x272 and for
the “bckgnd#.png” images, I clipped some basic pictures to this size.
Similarly, the font used is an open-source Open Text font which should be
easy to find.

This is a resend because the original seemed to lose formatting (hopefully this one won’t).


Please reply back with any questions or comments,

myke



/*
* dfb_image6.c
*
*
* Save and Later Redisplay Surface on the display
*
* Written for fsl i.MX233 EVK running Linux 2.6.31
*
*
* Created on: 29-Dec-2011
* Author: myke
*/

#include <stdio.h>
#include <unistd.h>
#include <directfb.h>



static IDirectFB* dfb = NULL;
static IDirectFBSurface* primary = NULL;
DFBSurfaceDescription primary_dsc;
static IDirectFBSurface* image1;
DFBSurfaceDescription image1_dsc;
static IDirectFBSurface* image2;
DFBSurfaceDescription image2_dsc;
static IDirectFBSurface* image3;
DFBSurfaceDescription image3_dsc;

IDirectFBFont* font = NULL;
DFBFontDescription font_dsc;

static int screen_width = 0;
static int screen_height = 0;


#define DFBCHECK(x...) \
{ \
DFBResult err = x; \
\
if (err != DFB_OK) \
{ \
fprintf( stderr, "%s <%d>:\n\t", __FILE__, __LINE__ ); \
DirectFBErrorFatal( #x, err ); \
} \
}

int main (int argc, char **argv)
{
int i;
IDirectFBImageProvider* provider;


// Create Super Interface
DFBCHECK(DirectFBInit (&argc, &argv));
DFBCHECK(DirectFBCreate (&dfb));

// Create Primary Surface
DFBCHECK(dfb->SetCooperativeLevel(dfb, DFSCL_FULLSCREEN));
primary_dsc.flags = DSDESC_CAPS;
primary_dsc.caps = DSCAPS_PRIMARY | DSCAPS_DOUBLE;
DFBCHECK(dfb->CreateSurface(dfb, &primary_dsc, &primary));

// Get the size of the primary Display
DFBCHECK(primary->GetSize(primary, &screen_width, &screen_height));
// printf("\r#### - \"primary\" screen_width = %i, screen_height = %i\r\n", screen_width, screen_height);

// Create (1) - JUST a background image
DFBCHECK(dfb->CreateImageProvider(dfb, "/home/images/bckgnd1.png", &provider)); // Gears Background
DFBCHECK(provider->GetSurfaceDescription(provider, &image1_dsc));
DFBCHECK(dfb->CreateSurface(dfb, &image1_dsc, &image1));
DFBCHECK(provider->RenderTo(provider, image1, NULL));
DFBCHECK(provider->Release(provider));

// Create (2) - NO background image
image2_dsc.flags = DSDESC_WIDTH | DSDESC_HEIGHT;
image2_dsc.width = screen_width; image2_dsc.height = screen_height;
DFBCHECK(dfb->CreateSurface(dfb, &image2_dsc, &image2));
font_dsc.flags = DFDESC_HEIGHT | DFDESC_ROTATION;
font_dsc.height = 24;
font_dsc.rotation = DFB_DEGREES(0);
DFBCHECK(dfb->CreateFont(dfb, "/home/fonts/NotCourierSans-Bold.otf", &font_dsc, &font));
DFBCHECK(image2->SetFont(image2, font));
DFBCHECK(image2->SetColor(image2, 0x00, 0x00, 0xff, 0xff));
DFBCHECK(image2->FillRectangle(image2, 0, 0, screen_width, screen_height));
DFBCHECK(image2->SetColor(image2, 0xff, 0xff, 0xff, 0xff));
DFBCHECK(image2->DrawString(image2, "Image (2)", -1, 25, screen_height / 2, DSTF_LEFT | DSTF_TOP));

// Create (3) - Background image & Box
DFBCHECK(dfb->CreateImageProvider(dfb, "/home/images/bckgnd2.png", &provider)); // Gears Background
DFBCHECK(provider->GetSurfaceDescription(provider, &image3_dsc));
DFBCHECK(dfb->CreateSurface(dfb, &image3_dsc, &image3));
DFBCHECK(provider->RenderTo(provider, image3, NULL));
DFBCHECK(provider->Release(provider));
DFBCHECK(image3->SetColor(image3, 0xff, 0xff, 0xff, 0xff));
DFBCHECK(image3->FillRectangle(image3, screen_width / 4, screen_height / 4, screen_width / 2, screen_height / 2));

// Display the First Image
DFBCHECK(primary->SetBlittingFlags(primary, DSBLIT_NOFX));
DFBCHECK(primary->Blit(primary, image1, NULL, 0, 0));
DFBCHECK(primary->Flip(primary, NULL, DSFLIP_ONSYNC));

sleep(1);


// Display the Second Image
DFBCHECK(primary->SetBlittingFlags(primary, DSBLIT_NOFX));
DFBCHECK(primary->Blit(primary, image2, NULL, 0, 0));
DFBCHECK(primary->Flip(primary, NULL, DSFLIP_ONSYNC));

sleep(1);