1 /*
2 * Copyright 2022 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 package androidx.compose.ui.text
18
19 import androidx.compose.runtime.Composable
20 import androidx.compose.runtime.remember
21 import androidx.compose.ui.platform.LocalDensity
22 import androidx.compose.ui.platform.LocalFontFamilyResolver
23 import androidx.compose.ui.platform.LocalLayoutDirection
24
25 /** This value should reflect the default cache size for TextMeasurer. */
26 private val DefaultCacheSize: Int = 8
27
28 /**
29 * Creates and remembers a [TextMeasurer]. All parameters that are required for [TextMeasurer]
30 * except [cacheSize] are read from CompositionLocals. Created [TextMeasurer] carries an internal
31 * [TextLayoutCache] with [cacheSize] capacity. Provide 0 for [cacheSize] to opt-out from internal
32 * caching behavior.
33 *
34 * @param cacheSize Capacity of internal cache inside [TextMeasurer]. Size unit is the number of
35 * unique text layout inputs that are measured. Value of this parameter highly depends on the
36 * consumer use case. Provide a cache size that is in line with how many distinct text layouts are
37 * going to be calculated by this measurer repeatedly. If you are animating font attributes, or
38 * any other layout affecting input, cache can be skipped because most repeated measure calls
39 * would miss the cache.
40 */
41 @Composable
rememberTextMeasurernull42 fun rememberTextMeasurer(cacheSize: Int = DefaultCacheSize): TextMeasurer {
43 val fontFamilyResolver = LocalFontFamilyResolver.current
44 val density = LocalDensity.current
45 val layoutDirection = LocalLayoutDirection.current
46
47 return remember(fontFamilyResolver, density, layoutDirection, cacheSize) {
48 TextMeasurer(fontFamilyResolver, density, layoutDirection, cacheSize)
49 }
50 }
51