Sliding over SVG? about lunasvg

[sammycage]

@erentknn With the latest commit you can now do this 7a175d4

Bitmap bitmap{width, height};
Matrix matrix{1, 0, 0, 1, -x, -y};
document->render(bitmap, matrix);

Hope that this will solve this problem.

[erentknn]

sure, svg.zip

[erentknn]

Here it is, for explanation x and y are the original coordinates in the original image (think like I have 40k x 40k image and this is a small piece in it) and I am shifting to that coordinates so I can render the right place. It's the same as in svgImage->translate(). But I provided this in the svg file for you so probably those are, shifting coordinates, unnecessary now. I hope that has been explanatory.

	const auto svgStrPtr = new char[svgStr.length() + 1];
	svgStrPtr[svgStr.length()] = '\0';
	strcpy(svgStrPtr, svgStr.c_str());
	nsvgImage = nsvgParse(svgStrPtr, "px", 96.0f);

	auto rast = nsvgCreateRasterizer(); // Create rasterizer
	auto img = static_cast<unsigned char*>(malloc(widthCalc * heightCalc * 4)); 
	nsvgRasterize(rast, nsvgImage, -x, -y, 1, img, widthCalc, heightCalc, widthCalc * 4); 
	auto res = cv::Mat(heightCalc, widthCalc, CV_8UC4);
	res.data = img;
	cv::cvtColor(res, res, CV_RGBA2GRAY);
	res = res > 0;
	nsvgDeleteRasterizer(rast); 
	free(img);

[sammycage]

Thanks. I will work on it this weekend.

[sammycage]

Please can you give me the SVG file

[sammycage]

sure, svg.zip

The SVG renders nothing

[erentknn]

oops, sorry. fixed it now: svg.zip

[sammycage]

With nanosvg I could do this with no overhead.

Please can you give me the nanosvg example code so that I can fully understand what you are trying to do.

[sammycage]

@erentknn if you are still having issues. Please let me know

[erentknn]

Hey @sammycage, thank you for quick response. but unfortunately it's still not working. I am using the same code as above.

[sammycage]

Sample code

auto document = Document::loadFromData("a.svg");
document->translate(-50, -50);

Before :

After :

[sammycage]

But I provided this in the svg file for you so probably those are, shifting coordinates, unnecessary now.

Please make sure that you are not using the modified file

[erentknn]

I think I explained the problem wrong. Translating works OK. What I am trying to do is sliding over the SVG Image, with nanosvg in my first output is like this:

and second is this:

Second image is the tagged area (approximately):

Like this, I want to loop on the whole SVG tile by tile.
BTW after your modification I can't get any output. Just blank image.

[sammycage]

@erentknn Did you mean Scaling?

[sammycage]

@erentknn is the height and width in lunasvg::Bitmap bitmap = svgImage->renderToBitmap(width, height) different from the one in the file.

[sammycage]

However I want to process this normally big (7k x 7k) image tile by tile.

Now I understand what you are trying to do

Use Document::render instead

Example :

Bitmap bitmap{width, height};
document->translate(-x, -y);
document->render(bitmap);

[erentknn]

@erentknn is the height and width in lunasvg::Bitmap bitmap = svgImage->renderToBitmap(width, height) different from the one in the file.

Yes, width and height are 1024.

Now I understand what you are trying to do

Use Document::render instead

Example :

Bitmap bitmap{width, height};
document->translate(-x, -y);
document->render(bitmap);

Now I can render the first tile correctly. But after that it's blank image again.

[erentknn]

THANK YOU, It worked as expected.