Blitting surface on another surface

SDL Development
1

Hi,
I am trying to make a text input widget by drawing text onto the mask (made as PNG) like this:

apply_surface(  SCREEN_WIDTH, SCREEN_HEIGHT, m_text, m_mask ); 
apply_surface(  SCREEN_WIDTH, SCREEN_HEIGHT, m_mask, screen );

but nothing happens when I type.Maybe somebody can give advice on how to do this?

dekyco

2

Does the mask have an alpha channel? You might have to disable alpha
blending with SDL_SetAlpha() in order to combine surfaces with alpha
channels. If you don’t, SDL will use the destination alpha. Of course,
re-enable it after the blit.

Jonny DOn Wed, Feb 10, 2010 at 10:03 AM, dekyco wrote:

Hi,
I am trying to make a text input widget by drawing text onto the mask (made
as PNG) like this:

apply_surface( SCREEN_WIDTH, SCREEN_HEIGHT, m_text, m_mask );
apply_surface( SCREEN_WIDTH, SCREEN_HEIGHT, m_mask, screen );

but nothing happens when I type.Maybe somebody can give advice on how to do
this?

dekyco

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3

Thank you Jonny,
I would appriciate some example for this if you don’t mind

dekyco

4

dekyco wrote:

apply_surface(  SCREEN_WIDTH, SCREEN_HEIGHT, m_text, m_mask ); 
apply_surface(  SCREEN_WIDTH, SCREEN_HEIGHT, m_mask, screen );

nothing happens…

Hi

is apply_surface like this?

void apply_surface( int x, int y, SDL_Surface* source, SDL_Surface* destination )
{
SDL_Rect offset;
offset.x = x;
offset.y = y;
SDL_BlitSurface( source, NULL, destination, &offset );
}

you have to call it using the right x and y !!!

try with:

apply_surface(  0, 0, m_text, m_mask ); 
apply_surface(  0, 0, m_mask, screen );

of course you must upload the screen using

SDL_Flip( screen );

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