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Functions
| int | vips_draw_rect () |
| int | vips_draw_rect1 () |
| int | vips_draw_point () |
| int | vips_draw_point1 () |
| int | vips_draw_image () |
| int | vips_draw_mask () |
| int | vips_draw_mask1 () |
| int | vips_draw_line () |
| int | vips_draw_line1 () |
| int | vips_draw_circle () |
| int | vips_draw_circle1 () |
| int | vips_draw_flood () |
| int | vips_draw_flood1 () |
| int | vips_draw_smudge () |
Description
These operations directly modify the image. They do not thread, on 32-bitmachines they will be limited to 2GB images, and a little care needs to betaken if you use them as part of an image pipeline.They are mostly supposed to be useful for paintbox-style programs.
libvips operations are all functional: they take zero or more existing inputimages and generate zero or more new output images. Images arenever altered, you always create new images. This means libvips can cacheand thread very aggressively.
The downside is that creating entirely fresh images each time can be veryslow. libvips has a range of tricks to avoid these problems, but there arestill times when you really have to be able to modify an image. An examplemight be drawing a curved line from a set of straight line segments: if youneed to draw 1,000 straight lines, a 1,000 operation-deep pipeline is goingto be a slow way to do it. This is where the draw operations come in.
To use these operations, usevips_image_copy_memory() to make a privatememory copy of the image you want to modify, then call aseries of draw operations.
Once you are done drawing, return to normal use of vips operations. Any timeyou want to start drawing again, you'll need to copy again.
Functions
vips_draw_rect ()
intvips_draw_rect (VipsImage *image,double *ink,int n,int left,int top,int width,int height,...);
Optional arguments:
fill: fill the rect
Paint pixels withinleft,top,width,height inimage withink. Iffill is zero, just paint a 1-pixel-wide outline.
See also:vips_draw_circle().
Parameters
image | image to draw on | |
ink | value to draw. | [array length=n] |
n | length of ink array | |
left | area to paint | |
top | area to paint | |
width | area to paint | |
height | area to paint | |
... |
|
vips_draw_rect1 ()
intvips_draw_rect1 (VipsImage *image,double ink,int left,int top,int width,int height,...);
Optional arguments:
fill: fill the rect
Asvips_draw_rect(), but just take a single double forink.
See also:vips_draw_rect().
vips_draw_point ()
intvips_draw_point (VipsImage *image,double *ink,int n,int x,int y,...);
Asvips_draw_rect(), but draw a single pixel atx,y.
See also:vips_draw_rect().
Parameters
image | image to draw on | |
ink | value to draw. | [array length=n] |
n | length of ink array | |
x | point to paint | |
y | point to paint | |
... |
|
vips_draw_point1 ()
intvips_draw_point1 (VipsImage *image,double ink,int x,int y,...);
Asvips_draw_point(), but just take a single double forink.
See also:vips_draw_point().
vips_draw_image ()
intvips_draw_image (VipsImage *image,VipsImage *sub,int x,int y,...);
Optional arguments:
mode: how to combine pixels
Drawsub on top ofimage at positionx,y. The two images must have thesame Coding. Ifsub has 1 band, the bands will be duplicated to match thenumber of bands inimage.sub will be converted toimage's format, seevips_cast().
Usemode to set how pixels are combined. If you useVIPS_COMBINE_MODE_ADD, both images muct be uncoded.
See also:vips_draw_mask(),vips_insert().
vips_draw_mask ()
intvips_draw_mask (VipsImage *image,double *ink,int n,VipsImage *mask,int x,int y,...);
Drawmask on the image.mask is a monochrome 8-bit image with 0/255for transparent orink coloured points. Intermediate values blend the inkwith the pixel. Use withvips_text() to draw text on an image. Use in avips_draw_line() subclass to draw an object along a line.
ink is an array of double containing values to draw.
See also:vips_text(),vips_draw_line().
Parameters
image | image to draw on | |
ink | value to draw. | [array length=n] |
n | size of ink array | |
mask | mask of 0/255 values showing where to plot | |
x | draw mask here | |
y | draw mask here | |
... |
|
vips_draw_mask1 ()
intvips_draw_mask1 (VipsImage *image,double ink,VipsImage *mask,int x,int y,...);
Asvips_draw_mask(), but just takes a single double forink.
See also:vips_draw_mask().
vips_draw_line ()
intvips_draw_line (VipsImage *image,double *ink,int n,int x1,int y1,int x2,int y2,...);
Draws a 1-pixel-wide line on an image.
ink is an array of double containing values to draw.
See also:vips_draw_line1(),vips_draw_circle(),vips_draw_mask().
Parameters
image | image to draw on | |
ink | value to draw. | [array length=n] |
n | length of ink array | |
x1 | start of draw_line | |
y1 | start of draw_line | |
x2 | end of draw_line | |
y2 | end of draw_line | |
... |
|
vips_draw_line1 ()
intvips_draw_line1 (VipsImage *image,double ink,int x1,int y1,int x2,int y2,...);
Asvips_draw_line(), but just take a single double forink.
See also:vips_draw_line().
vips_draw_circle ()
intvips_draw_circle (VipsImage *image,double *ink,int n,int cx,int cy,int radius,...);
Optional arguments:
fill: fill the draw_circle
Draws a circle onimage. Iffill isTRUE then the circle is filled,otherwise a 1-pixel-wide perimeter is drawn.
ink is an array of double containing values to draw.
See also:vips_draw_circle1(),vips_draw_line().
Parameters
image | image to draw on | |
ink | value to draw. | [array length=n] |
n | length of ink array | |
cx | centre of draw_circle | |
cy | centre of draw_circle | |
radius | draw_circle radius | |
... |
|
vips_draw_circle1 ()
intvips_draw_circle1 (VipsImage *image,double ink,int cx,int cy,int radius,...);
Optional arguments:
fill: fill the draw_circle
Asvips_draw_circle(), but just takes a single double forink.
See also:vips_draw_circle().
vips_draw_flood ()
intvips_draw_flood (VipsImage *image,double *ink,int n,int x,int y,...);
Optional arguments:
test: test this imageequal: fill while equal to edgeleft: output left edge of bounding box of modified areatop: output top edge of bounding box of modified areawidth: output width of bounding box of modified areaheight: output height of bounding box of modified area
Flood-fillimage withink, starting at positionx,y. The filled area isbounded by pixels that are equal to the ink colour, in other words, itsearches for pixels enclosed by an edge ofink.
Ifequal is set, it instead searches for pixels which are equal to thestart point and fills them withink.
Normally it will test and set pixels inimage. Iftest is set, it willtest pixels intest and set pixels inimage. This lets you search animage (test) for continuous areas of pixels without modifying it.
left,top,width,height output the bounding box of the modifiedpixels.
ink is an array of double containing values to draw.
See also:vips_draw_flood1().
Parameters
image | image to draw on | |
ink | value to draw. | [array length=n] |
n | length of ink array | |
x | centre of circle | |
y | centre of circle | |
... |
|
vips_draw_flood1 ()
intvips_draw_flood1 (VipsImage *image,double ink,int x,int y,...);
Optional arguments:
test: test this imageequal: fill while equal to edgeleft: output left edge of bounding box of modified areatop: output top edge of bounding box of modified areawidth: output width of bounding box of modified areaheight: output height of bounding box of modified area
Asvips_draw_flood(), but just takes a single double forink.
See also:vips_draw_flood().
vips_draw_smudge ()
intvips_draw_smudge (VipsImage *image,int left,int top,int width,int height,...);
Smudge a section ofimage. Each pixel in the arealeft,top,width,height is replaced by the average of the surrounding 3x3 pixels.
See also:vips_draw_line().
Types and Values
enum VipsCombineMode
Seevips_draw_image() and so on.
Operations likevips_draw_image() need to be told how to combine imagesfrom two sources.
See also:vips_join().
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