TextShaper Classe

Definizione

[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

Ereditarietà

Object

JavaObject

Object

TextShaper

Attributi

RegisterAttribute

Commenti

Fornisce la forma del testo per il testo con più stili.

Di seguito è riportato un esempio di animazione delle dimensioni del testo e della spaziatura delle lettere per il testo semplice.

<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&lt;Pair&lt;PositionedGlyphs, DrawStyle&gt;&gt;()
                private val end = mutableListOf&lt;Pair&lt;PositionedGlyphs, DrawStyle&gt;&gt;()

                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>

per android.text.TextShaper.

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