danieleghisi

Hi, i need to paint rotated copies of a given jsurface.

jgraphics_rotate(g, 0.2);
jgraphics_image_surface_draw(g, my_surface, source_rect, dest_rect);

but it doesn't work. This might make sense since apparently jgraphics_image_surface_draw does not support rotations.

rotated-copies-of-surface

u may try to use jgraphics_rotate before your jgraphics_image_surface_draw method .


Hi Do...while, actually my example was wrongly extrapolated – sorry (I've fixed it). It was inside a for loop, so I'm 100% sure that the function are called in the proper order. However, no rotation appears, only a weird shear of the image.

ok , thats weird . can u post how the output image looks like after all (these weird shears)?

Well, actually that's no shear, just a non-uniform scaling. Here's what happens with these lines of code!

http://data.danieleghisi.com/video/rotation_issue.mov

Code ("temp" is the angle, lena is charged with the standard lena png image):

t_jsurface *lena = jgraphics_image_surface_create_from_file(filename, path);
double height = jgraphics_image_surface_get_height(lena);
double width = jgraphics_image_surface_get_width(lena);
jgraphics_rotate(g, x->temp);
jgraphics_image_surface_draw(g, lena, build_rect(0, 0, width, height), build_rect(0, 0, rect.width, rect.height));

Does anybody know which is the most efficient way to bypass this issue?

Well, actually that's no shear, just a non-uniform scaling. Here's what happens with these lines of code! 

Video:
http://data.danieleghisi.com/video/rotation_issue.mov

Does anybody know which is the most efficient way to bypass this issue?


ok . i cant prove it now but working directly on a image_surface will distort its source . you could use it as a 

 . i remember the same issue with JavaScript , where ive been in need to set source as a pattern first . Does SDK provide pattern setup ? . sorry i cant look into SDK right now

ok . i cant prove it now but working directly on a image_surface will distort its source . you could use it as a pattern . i remember the same issue with JavaScript , where ive been in need to set source as a pattern first . Does SDK provide pattern setup ? . sorry i cant look into SDK right now


Hi Do...while, actually using patterns has partially solved my issue. Now I'm able to rotate the image.

However, I don't seem to be able to put in the same graphic context both the image (say, inside a portion of it), and its rotated copy (inside another portion of it). Apparently the rotation applies to all portions of the graphic context.

Hi Do...while, actually using patterns has partially solved my issue. Now I'm able to rotate the image.
However, I don't seem to be able to put in the same graphic context both the image (say, inside a portion of it), and its rotated copy (inside another portion of it). Apparently the rotation applies to all portions of the graphic context.

Although I guess the only solution is to create a pattern for each portion (which unfortunately makes a lot of patterns, in my case...)

yes u need work with pattern instances separately :/ but its just a bit more of a code (yeah might become messy), i cant say that its much less efficient way even if it adds another layer to manage .

Rotated copies of surface