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sprite_trim

Script for GM:Studio.
Remove the pixels with alpha 0 from the borders

Returns a new sprite or -1 for error.

Arguments

sprite : the sprite to trim
subimg : the frame of the sprite

Returns : sprite

Source code

```
///sprite_trim(sprite, subimg)
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```
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if(!sprite_exists(argument0))
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    return -1;
```
```
 
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var w = sprite_get_width(argument0);
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var h = sprite_get_height(argument0);
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var xo = sprite_get_xoffset(argument0);
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var yo = sprite_get_yoffset(argument0);
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var s = surface_create(w, h);
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surface_set_target(s);
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draw_clear_alpha(0, 0);
```

draw_sprite(argument0, argument1, xo, yo);

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surface_reset_target();
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var buf = buffer_create(w * h * 4, buffer_fixed, 4);

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buffer_get_surface(buf, s, 0, 0, 0);
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var xx, yy, pixel, a;
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var left = 0, top = 0, right = 0, bottom = 0;

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//left
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for(xx = 0; xx < w; xx++)
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{   
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    for(yy = 0; yy < h; yy++)
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    {
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        pixel = buffer_peek(buf, (xx + yy * w) * 4, buffer_u32);

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        a = (pixel >> 24) & 255;
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        if(a != 0)
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            break;
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    }
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    if(a != 0)
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        break;
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    else
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        left++;
```
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}
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```
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//top
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for(yy = 0; yy < h; yy++)
```
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{
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    for(xx = 0; xx < w; xx++)
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    {   
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        pixel = buffer_peek(buf, (xx + yy * w) * 4, buffer_u32);

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        a = (pixel >> 24) & 255;
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        if(a != 0)
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            break;
```
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    }
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    if(a != 0)
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        break;
```
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    else
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        top++;
```
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}
```
```
 
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//right
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for(xx = w-1; xx >= 0; xx--)
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{   
```
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    for(yy = 0; yy < h; yy++)
```
```
    {
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        pixel = buffer_peek(buf, (xx + yy * w) * 4, buffer_u32);

```
        a = (pixel >> 24) & 255;
```
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        if(a != 0)
```
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            break;
```
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    }
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    if(a != 0)
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        break;
```
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    else
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        right++;
```
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}
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//bottom
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for(yy = h-1; yy >= 0; yy--)
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{
```
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    for(xx = 0; xx < w; xx++)
```
```
    {   
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        pixel = buffer_peek(buf, (xx + yy * w) * 4, buffer_u32);

```
        a = (pixel >> 24) & 255;
```
```
        if(a != 0)
```
```
            break;
```
```
    }
```
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    if(a != 0)
```
```
        break;
```
```
    else
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        bottom++;
```
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}
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```
 
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buffer_delete(buf);
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surface_free(s)
```

return sprite_create_from_surface(s, left, top, w-left-right, h-top-bottom, 0, 0, xo-left, yo-top);

```
 
```

by Tizsoft in 2015-07-12 11:15:46.