mazatech / amanithvg-sdk Goto Github PK

make easier to use amanithvg in cmake projects

similar: vpxyz/ShivaVG#4

use case: im trying to link the ShivaVG examples to libAmanithVG.so

Hi,
Not a bug
Just request library for Apple M1

Thank you in Advance

When a string of text is drawn with vgDrawGlyphs, it seems to be reading the adjustment values from the wrong locations in the provided array. For character 0, it is not using any adjustment value, only using the position set to VG_GLYPH_ORIGIN. For character 1, it uses the adjustment value in adjustments[0].

To demonstrate, if I had the following code:

VGuint indices[strlen];
VGfloat x_adjustments[strlen];
VGfloat y_adjustments[strlen];

for (int i = 0; i < strlen; i++) {

    /* Find computed values */

    indices[i] = computed_index;
    x_adjustments[i] = computed_x_adjustment;
    y_adjustments[i] = computed_y_adjustment;
}

vgSetfv (VG_GLYPH_ORIGIN, 2, overall_origin);
vgDrawGlyphs (font,
              strlen,
              indices,
              x_adjustments,
              y_adjustments,
              VG_FILL_PATH,
              VG_FALSE);

I would have to change it to this for it to use the adjustment value on character 0 and the correct adjustments on the following characters:

VGuint indices[strlen];
VGfloat x_adjustments[strlen];
VGfloat y_adjustments[strlen];

for (int i = 0; i < strlen; i++) {

    /* Find computed values */

    indices[i] = computed_index;
    x_adjustments[i] = computed_x_adjustment;
    y_adjustments[i] = computed_y_adjustment;
}

VGfloat[2] new_overall_origin = {overall_origin[0] + x_adjustments[0], overall_origin[1] + y_adjustments[0]};
vgSetfv (VG_GLYPH_ORIGIN, 2, new_overall_origin);
vgDrawGlyphs (font,
              strlen,
              indices,
              &x_adjustments[1],
              &y_adjustments[1],
              VG_FILL_PATH,
              VG_FALSE);

However, the specification does seem somewhat ambiguous about this, as it says:

The user space position of the first glyph (the point where the glyph origin will be placed) is determined by the value of VG_GLYPH_ORIGIN.

Contrary to one possible interpretation of that, it seems that many applications written against OpenVG use vgDrawGlyphs adjustments as if the 0th value will be used.

Thank you for taking the time to read this. If I could provide any more information, please let me know.