TextShaper Class
Definition
Important
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Provides text shaping for multi-styled text.
[Android.Runtime.Register("android/text/TextShaper", ApiSince=31, DoNotGenerateAcw=true)]
public class TextShaper : Java.Lang.Object[<Android.Runtime.Register("android/text/TextShaper", ApiSince=31, DoNotGenerateAcw=true)>]
type TextShaper = class
inherit Object- Inheritance
- Attributes
Remarks
Provides text shaping for multi-styled text.
Here is an example of animating text size and letter spacing for simple text.
<code>
// In this example, shape the text once for start and end state, then animate between two shape
// result without re-shaping in each frame.
class SimpleAnimationView @JvmOverloads constructor(
context: Context,
attrs: AttributeSet? = null,
defStyleAttr: Int = 0
) : View(context, attrs, defStyleAttr) {
private val textDir = TextDirectionHeuristics.LOCALE
private val text = "Hello, World." // The text to be displayed
// Class for keeping drawing parameters.
data class DrawStyle(val textSize: Float, val alpha: Int)
// The start and end text shaping result. This class will animate between these two.
private val start = mutableListOf<Pair<PositionedGlyphs, DrawStyle>>()
private val end = mutableListOf<Pair<PositionedGlyphs, DrawStyle>>()
init {
val startPaint = TextPaint().apply {
alpha = 0 // Alpha only affect text drawing but not text shaping
textSize = 36f // TextSize affect both text shaping and drawing.
letterSpacing = 0f // Letter spacing only affect text shaping but not drawing.
}
val endPaint = TextPaint().apply {
alpha = 255
textSize =128f
letterSpacing = 0.1f
}
TextShaper.shapeText(text, 0, text.length, textDir, startPaint) { _, _, glyphs, paint ->
start.add(Pair(glyphs, DrawStyle(paint.textSize, paint.alpha)))
}
TextShaper.shapeText(text, 0, text.length, textDir, endPaint) { _, _, glyphs, paint ->
end.add(Pair(glyphs, DrawStyle(paint.textSize, paint.alpha)))
}
}
override fun onDraw(canvas: Canvas) {
super.onDraw(canvas)
// Set the baseline to the vertical center of the view.
canvas.translate(0f, height / 2f)
// Assume the number of PositionedGlyphs are the same. If different, you may want to
// animate in a different way, e.g. cross fading.
start.zip(end) { (startGlyphs, startDrawStyle), (endGlyphs, endDrawStyle) ->
// Tween the style and set to paint.
paint.textSize = lerp(startDrawStyle.textSize, endDrawStyle.textSize, progress)
paint.alpha = lerp(startDrawStyle.alpha, endDrawStyle.alpha, progress)
// Assume the number of glyphs are the same. If different, you may want to animate in
// a different way, e.g. cross fading.
require(startGlyphs.glyphCount() == endGlyphs.glyphCount())
if (startGlyphs.glyphCount() == 0) return@zip
var curFont = startGlyphs.getFont(0)
var drawStart = 0
for (i in 1 until startGlyphs.glyphCount()) {
// Assume the pair of Glyph ID and font is the same. If different, you may want
// to animate in a different way, e.g. cross fading.
require(startGlyphs.getGlyphId(i) == endGlyphs.getGlyphId(i))
require(startGlyphs.getFont(i) === endGlyphs.getFont(i))
val font = startGlyphs.getFont(i)
if (curFont != font) {
drawGlyphs(canvas, startGlyphs, endGlyphs, drawStart, i, curFont, paint)
curFont = font
drawStart = i
}
}
if (drawStart != startGlyphs.glyphCount() - 1) {
drawGlyphs(canvas, startGlyphs, endGlyphs, drawStart, startGlyphs.glyphCount(),
curFont, paint)
}
}
}
// Draws Glyphs for the same font run.
private fun drawGlyphs(canvas: Canvas, startGlyph: PositionedGlyphs,
endGlyph: PositionedGlyphs, start: Int, end: Int, font: Font,
paint: Paint) {
var cacheIndex = 0
for (i in start until end) {
intArrayCache[cacheIndex] = startGlyph.getGlyphId(i)
// The glyph positions are different from start to end since they are shaped
// with different letter spacing. Use linear interpolation for positions
// during animation.
floatArrayCache[cacheIndex * 2] =
lerp(startGlyph.getGlyphX(i), endGlyph.getGlyphX(i), progress)
floatArrayCache[cacheIndex * 2 + 1] =
lerp(startGlyph.getGlyphY(i), endGlyph.getGlyphY(i), progress)
if (cacheIndex == CACHE_SIZE) { // Cached int array is full. Flashing.
canvas.drawGlyphs(
intArrayCache, 0, // glyphID array and its starting offset
floatArrayCache, 0, // position array and its starting offset
cacheIndex, // glyph count
font,
paint
)
cacheIndex = 0
}
cacheIndex++
}
if (cacheIndex != 0) {
canvas.drawGlyphs(
intArrayCache, 0, // glyphID array and its starting offset
floatArrayCache, 0, // position array and its starting offset
cacheIndex, // glyph count
font,
paint
)
}
}
// Linear Interpolator
private fun lerp(start: Float, end: Float, t: Float) = start * (1f - t) + end * t
private fun lerp(start: Int, end: Int, t: Float) = (start * (1f - t) + end * t).toInt()
// The animation progress.
var progress: Float = 0f
set(value) {
field = value
invalidate()
}
// working copy of paint.
private val paint = Paint()
// Array cache for reducing allocation during drawing.
private var intArrayCache = IntArray(CACHE_SIZE)
private var floatArrayCache = FloatArray(CACHE_SIZE * 2)
}
</code>
Java documentation for android.text.TextShaper.
Portions of this page are modifications based on work created and shared by the Android Open Source Project and used according to terms described in the Creative Commons 2.5 Attribution License.
Constructors
| TextShaper(IntPtr, JniHandleOwnership) |
Properties
| Class |
Returns the runtime class of this |
| Handle |
The handle to the underlying Android instance. (Inherited from Object) |
| JniIdentityHashCode | (Inherited from Object) |
| JniPeerMembers | |
| PeerReference | (Inherited from Object) |
| ThresholdClass | |
| ThresholdType | |
Methods
| Clone() |
Creates and returns a copy of this object. (Inherited from Object) |
| Dispose() | (Inherited from Object) |
| Dispose(Boolean) | (Inherited from Object) |
| Equals(Object) |
Indicates whether some other object is "equal to" this one. (Inherited from Object) |
| GetHashCode() |
Returns a hash code value for the object. (Inherited from Object) |
| JavaFinalize() |
Called by the garbage collector on an object when garbage collection determines that there are no more references to the object. (Inherited from Object) |
| Notify() |
Wakes up a single thread that is waiting on this object's monitor. (Inherited from Object) |
| NotifyAll() |
Wakes up all threads that are waiting on this object's monitor. (Inherited from Object) |
| SetHandle(IntPtr, JniHandleOwnership) |
Sets the Handle property. (Inherited from Object) |
| ShapeText(ICharSequence, Int32, Int32, ITextDirectionHeuristic, TextPaint, TextShaper+IGlyphsConsumer) |
Shape multi-styled text. |
| ShapeText(String, Int32, Int32, ITextDirectionHeuristic, TextPaint, TextShaper+IGlyphsConsumer) |
Shape multi-styled text. |
| ToArray<T>() | (Inherited from Object) |
| ToString() |
Returns a string representation of the object. (Inherited from Object) |
| UnregisterFromRuntime() | (Inherited from Object) |
| Wait() |
Causes the current thread to wait until it is awakened, typically by being <em>notified</em> or <em>interrupted</em>. (Inherited from Object) |
| Wait(Int64) |
Causes the current thread to wait until it is awakened, typically by being <em>notified</em> or <em>interrupted</em>, or until a certain amount of real time has elapsed. (Inherited from Object) |
| Wait(Int64, Int32) |
Causes the current thread to wait until it is awakened, typically by being <em>notified</em> or <em>interrupted</em>, or until a certain amount of real time has elapsed. (Inherited from Object) |
Explicit Interface Implementations
| IJavaPeerable.Disposed() | (Inherited from Object) |
| IJavaPeerable.DisposeUnlessReferenced() | (Inherited from Object) |
| IJavaPeerable.Finalized() | (Inherited from Object) |
| IJavaPeerable.JniManagedPeerState | (Inherited from Object) |
| IJavaPeerable.SetJniIdentityHashCode(Int32) | (Inherited from Object) |
| IJavaPeerable.SetJniManagedPeerState(JniManagedPeerStates) | (Inherited from Object) |
| IJavaPeerable.SetPeerReference(JniObjectReference) | (Inherited from Object) |
Extension Methods
| JavaCast<TResult>(IJavaObject) |
Performs an Android runtime-checked type conversion. |
| JavaCast<TResult>(IJavaObject) | |
| GetJniTypeName(IJavaPeerable) | |