TextShaper Classe

Définition

[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

Héritage

Object

JavaObject

Object

TextShaper

Attributs

RegisterAttribute

Remarques

Fournit une mise en forme de texte pour le texte à styles multiples.

Voici un exemple d’animation de la taille du texte et de l’espacement des lettres pour du texte simple.

<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>

Java documentation pour android.text.TextShaper.

Les parties de cette page sont des modifications basées sur le travail créé et partagé par Android Open Source et utilisées en fonction des termes décrits dans la Creative Commons 2.5 Attribution License.