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Diffstat (limited to 'wallet/src/main/java/net/taler/wallet/compose/AmountInputField.kt')
| -rw-r--r-- | wallet/src/main/java/net/taler/wallet/compose/AmountInputField.kt | 226 |
1 files changed, 226 insertions, 0 deletions
diff --git a/wallet/src/main/java/net/taler/wallet/compose/AmountInputField.kt b/wallet/src/main/java/net/taler/wallet/compose/AmountInputField.kt new file mode 100644 index 0000000..a524d1b --- /dev/null +++ b/wallet/src/main/java/net/taler/wallet/compose/AmountInputField.kt @@ -0,0 +1,226 @@ +/* + * This file is part of GNU Taler + * (C) 2023 Taler Systems S.A. + * + * GNU Taler is free software; you can redistribute it and/or modify it under the + * terms of the GNU General Public License as published by the Free Software + * Foundation; either version 3, or (at your option) any later version. + * + * GNU Taler is distributed in the hope that it will be useful, but WITHOUT ANY + * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR + * A PARTICULAR PURPOSE. See the GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License along with + * GNU Taler; see the file COPYING. If not, see <http://www.gnu.org/licenses/> + */ + +package net.taler.wallet.compose + +import android.os.Build +import androidx.compose.foundation.text.KeyboardActions +import androidx.compose.foundation.text.KeyboardOptions +import androidx.compose.material3.LocalTextStyle +import androidx.compose.material3.OutlinedTextField +import androidx.compose.runtime.Composable +import androidx.compose.runtime.getValue +import androidx.compose.runtime.mutableStateOf +import androidx.compose.runtime.remember +import androidx.compose.runtime.setValue +import androidx.compose.ui.Modifier +import androidx.compose.ui.text.AnnotatedString +import androidx.compose.ui.text.font.FontFamily +import androidx.compose.ui.text.input.KeyboardType +import androidx.compose.ui.text.input.OffsetMapping +import androidx.compose.ui.text.input.TransformedText +import androidx.compose.ui.text.input.VisualTransformation +import net.taler.common.Amount +import java.text.DecimalFormat +import java.text.DecimalFormatSymbols +import kotlin.math.max +import kotlin.math.pow +import kotlin.math.roundToLong + +const val DEFAULT_INPUT_DECIMALS = 2 + +@Composable +fun AmountInputField( + value: String, + onValueChange: (value: String) -> Unit, + modifier: Modifier = Modifier, + label: @Composable (() -> Unit)? = null, + supportingText: @Composable (() -> Unit)? = null, + isError: Boolean = false, + keyboardActions: KeyboardActions = KeyboardActions.Default, + decimalFormatSymbols: DecimalFormatSymbols = DecimalFormat().decimalFormatSymbols, + numberOfDecimals: Int = DEFAULT_INPUT_DECIMALS, +) { + var amountInput by remember { mutableStateOf(value) } + + // React to external changes + val amountValue = remember(amountInput, value) { + transformOutput(amountInput).let { + if (value != it) transformInput(value, numberOfDecimals) else amountInput + } + } + + OutlinedTextField( + value = amountValue, + onValueChange = { input -> + if (input.matches("0+".toRegex())) { + amountInput = "0" + onValueChange("") + } else transformOutput(input, numberOfDecimals)?.let { filtered -> + if (Amount.isValidAmountStr(filtered) && !input.contains("-")) { + amountInput = input.trimStart('0') + onValueChange(filtered) + } + } + }, + modifier = modifier, + textStyle = LocalTextStyle.current.copy(fontFamily = FontFamily.Monospace), + label = label, + supportingText = supportingText, + isError = isError, + visualTransformation = AmountInputVisualTransformation( + symbols = decimalFormatSymbols, + fixedCursorAtTheEnd = true, + numberOfDecimals = numberOfDecimals, + ), + keyboardOptions = KeyboardOptions.Default.copy(keyboardType = KeyboardType.NumberPassword), + keyboardActions = keyboardActions, + singleLine = true, + maxLines = 1, + ) +} + +// 500 -> 5.0 +private fun transformOutput( + input: String, + numberOfDecimals: Int = 2, +) = if (input.isEmpty()) "0" else { + input.toLongOrNull()?.let { it / 10.0.pow(numberOfDecimals) }?.toBigDecimal()?.toPlainString() +} + +// 5.0 -> 500 +private fun transformInput( + output: String, + numberOfDecimals: Int = 2, +) = if (output.isEmpty()) "0" else { + (output.toDouble() * 10.0.pow(numberOfDecimals)).roundToLong().toString() +} + +// Source: https://github.com/banmarkovic/CurrencyAmountInput + +private class AmountInputVisualTransformation( + private val symbols: DecimalFormatSymbols, + private val fixedCursorAtTheEnd: Boolean = true, + private val numberOfDecimals: Int = 2, +): VisualTransformation { + + override fun filter(text: AnnotatedString): TransformedText { + val thousandsSeparator = if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.UPSIDE_DOWN_CAKE) { + symbols.monetaryGroupingSeparator + } else { + symbols.groupingSeparator + } + val decimalSeparator = symbols.monetaryDecimalSeparator + val zero = symbols.zeroDigit + + val inputText = text.text + + val intPart = inputText + .dropLast(numberOfDecimals) + .reversed() + .chunked(3) + .joinToString(thousandsSeparator.toString()) + .reversed() + .ifEmpty { + zero.toString() + } + + val fractionPart = inputText.takeLast(numberOfDecimals).let { + if (it.length != numberOfDecimals) { + List(numberOfDecimals - it.length) { + zero + }.joinToString("") + it + } else { + it + } + } + + // Hide trailing decimal separator if decimals are 0 + val formattedNumber = if (numberOfDecimals > 0) { + intPart + decimalSeparator + fractionPart + } else { + intPart + } + + val newText = AnnotatedString( + text = formattedNumber, + spanStyles = text.spanStyles, + paragraphStyles = text.paragraphStyles + ) + + val offsetMapping = if (fixedCursorAtTheEnd) { + FixedCursorOffsetMapping( + contentLength = inputText.length, + formattedContentLength = formattedNumber.length + ) + } else { + MovableCursorOffsetMapping( + unmaskedText = text.toString(), + maskedText = newText.toString(), + decimalDigits = numberOfDecimals + ) + } + + return TransformedText(newText, offsetMapping) + } + + private class FixedCursorOffsetMapping( + private val contentLength: Int, + private val formattedContentLength: Int, + ) : OffsetMapping { + override fun originalToTransformed(offset: Int): Int = formattedContentLength + override fun transformedToOriginal(offset: Int): Int = contentLength + } + + private class MovableCursorOffsetMapping( + private val unmaskedText: String, + private val maskedText: String, + private val decimalDigits: Int + ) : OffsetMapping { + override fun originalToTransformed(offset: Int): Int = + when { + unmaskedText.length <= decimalDigits -> { + maskedText.length - (unmaskedText.length - offset) + } + else -> { + offset + offsetMaskCount(offset, maskedText) + } + } + + override fun transformedToOriginal(offset: Int): Int = + when { + unmaskedText.length <= decimalDigits -> { + max(unmaskedText.length - (maskedText.length - offset), 0) + } + else -> { + offset - maskedText.take(offset).count { !it.isDigit() } + } + } + + private fun offsetMaskCount(offset: Int, maskedText: String): Int { + var maskOffsetCount = 0 + var dataCount = 0 + for (maskChar in maskedText) { + if (!maskChar.isDigit()) { + maskOffsetCount++ + } else if (++dataCount > offset) { + break + } + } + return maskOffsetCount + } + } +}
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