SkTextBlobBuilder Reference
===
---
class SkTextBlobBuilder {
SkTextBlobBuilder();
~SkTextBlobBuilder();
sk_sp<SkTextBlob> make();
const RunBuffer& allocRun(const SkFont& font, int count, SkScalar x, SkScalar y,
const SkRect* bounds = nullptr);
const RunBuffer& allocRunPosH(const SkFont& font, int count, SkScalar y,
const SkRect* bounds = nullptr);
const RunBuffer& allocRunPos(const SkFont& font, int count,
const SkRect* bounds = nullptr);
};
Helper class for constructing SkTextBlob.
---
struct RunBuffer {
SkGlyphID* glyphs;
SkScalar* pos;
char* utf8text;
uint32_t* clusters;
};
RunBuffer supplies storage for Glyphs and positions within a run.
A run is a sequence of Glyphs sharing Font_Metrics and positioning.
Each run may position its Glyphs in one of three ways:
by specifying where the first Glyph is drawn, and allowing Font_Metrics to
determine the advance to subsequent Glyphs; by specifying a baseline, and
the position on that baseline for each Glyph in run; or by providing Point
array, one per Glyph.
### See Also
allocRun allocRunPos allocRunPosH
---
SkTextBlobBuilder()
Constructs empty SkTextBlobBuilder. By default, SkTextBlobBuilder has no runs.
### Return Value
empty SkTextBlobBuilder
### Example
#### Example Output
~~~~
blob equals nullptr
~~~~
### See Also
make SkTextBlob::MakeFromText
---
~SkTextBlobBuilder()
Deletes data allocated internally by SkTextBlobBuilder.
### See Also
SkTextBlobBuilder()
---
sk_sp<SkTextBlob> make()
Returns SkTextBlob built from runs of glyphs added by builder. Returned
SkTextBlob is immutable; it may be copied, but its contents may not be altered.
Returns nullptr if no runs of glyphs were added by builder.
Resets SkTextBlobBuilder to its initial empty state, allowing it to be
reused to build a new set of runs.
### Return Value
SkTextBlob or nullptr
### Example
#### Example Output
~~~~
blob equals nullptr
blob does not equal nullptr
blob equals nullptr
~~~~
### See Also
SkTextBlob::MakeFromText
---
const RunBuffer& allocRun(const SkFont& font, int count, SkScalar x, SkScalar y,
const SkRect* bounds = nullptr)
Returns run with storage for glyphs. Caller must write count glyphs to
RunBuffer::glyphs before next call to SkTextBlobBuilder.
RunBuffer::utf8text, and RunBuffer::clusters should be ignored.
Glyphs share metrics in font.
Glyphs are positioned on a baseline at (x, y), using font metrics to
determine their relative placement.
bounds defines an optional bounding box, used to suppress drawing when SkTextBlob
bounds does not intersect SkSurface bounds. If bounds is nullptr, SkTextBlob bounds
is computed from (x, y) and RunBuffer::glyphs metrics.
### Parameters
font |
SkFont used for this run |
count |
number of glyphs |
x |
horizontal offset within the blob |
y |
vertical offset within the blob |
bounds |
optional run bounding box |
### Return Value
writable glyph buffer
### Example
### See Also
allocRunPosH allocRunPos
---
const RunBuffer& allocRunPosH(const SkFont& font, int count, SkScalar y,
const SkRect* bounds = nullptr)
Returns run with storage for glyphs and positions along baseline. Caller must
write count glyphs to RunBuffer::glyphs, and count scalars to RunBuffer::pos;
before next call to SkTextBlobBuilder.
RunBuffer::utf8text, and RunBuffer::clusters should be ignored.
Glyphs share metrics in font.
Glyphs are positioned on a baseline at y, using x-axis positions written by
caller to RunBuffer::pos.
bounds defines an optional bounding box, used to suppress drawing when SkTextBlob
bounds does not intersect SkSurface bounds. If bounds is nullptr, SkTextBlob bounds
is computed from y, RunBuffer::pos, and RunBuffer::glyphs metrics.
### Parameters
### Return Value
writable glyph buffer and x-axis position buffer
### Example
### See Also
allocRunPos allocRun
---
const RunBuffer& allocRunPos(const SkFont& font, int count, const SkRect* bounds = nullptr)
Returns run with storage for glyphs and SkPoint positions. Caller must
write count glyphs to RunBuffer::glyphs, and count SkPoint to RunBuffer::pos;
before next call to SkTextBlobBuilder.
RunBuffer::utf8text, and RunBuffer::clusters should be ignored.
Glyphs share metrics in font.
Glyphs are positioned using SkPoint written by caller to RunBuffer::pos, using
two scalar values for each SkPoint.
bounds defines an optional bounding box, used to suppress drawing when SkTextBlob
bounds does not intersect SkSurface bounds. If bounds is nullptr, SkTextBlob bounds
is computed from RunBuffer::pos, and RunBuffer::glyphs metrics.
### Parameters
### Return Value
writable glyph buffer and SkPoint buffer
### Example
### See Also
allocRunPosH allocRun