app: Add relay fee setting

Add a relay fee to settings and allow changing. The fee is not yet used.

Save the relay fee with the account. Allow changing of the relay fee in
Account settings as apposed to App settings. Change relay fee input
field to radio buttons with labels low, default, and high. Set
appropriate values for low (4000) and high (114000).

decred/decred/dcr/account.py

@@ -7,6 +7,7 @@
 from decred import DecredError
 from decred.crypto import crypto, opcode
 from decred.dcr import addrlib
+from decred.dcr.txscript import DefaultRelayFeePerKb
 from decred.util import encode, helpers
 from decred.util.encode import BuildyBytes, ByteArray, unblobCheck
 
@@ -801,6 +802,7 @@ def __init__(
         self.coinID = BIPID
         self.netID = netID
         self.netParams = nets.parse(netID)
+        self.relayFee = int(DefaultRelayFeePerKb)
         # For external addresses, the cursor can sit on the last seen address,
         # so start the lastSeen at the 0th external address. This is necessary
         # because the currentAddress method grabs the address at the current
@@ -856,14 +858,15 @@ def blob(acct):
             .addData(encode.intToBytes(acct.cursorExt, signed=True))
             .addData(acct.cursorInt)
             .addData(acct.gapLimit)
+            .addData(acct.relayFee)
             .b
         )
 
     @staticmethod
     def unblob(b):
         """Satisfies the encode.Blobber API"""
         ver, d = encode.decodeBlob(b)
-        unblobCheck("Account", ver, len(d), {0: 8})
+        unblobCheck("Account", ver, len(d), {0: 9})
 
         iFunc = encode.intFromBytes
 
@@ -876,6 +879,7 @@ def unblob(b):
         acct.cursorExt = iFunc(d[5], signed=True)
         acct.cursorInt = iFunc(d[6])
         acct.gapLimit = iFunc(d[7])
+        acct.relayFee = iFunc(d[8])
         return acct
 
     @staticmethod

tinywallet/tinywallet/screens.py

@@ -18,6 +18,7 @@
 from decred.crypto import crypto
 from decred.dcr import constants as DCR, nets
 from decred.dcr.blockchain import LocalNode
+from decred.dcr.txscript import DefaultRelayFeePerKb
 from decred.dcr.vsp import VotingServiceProvider
 from decred.util import chains, database, helpers
 from decred.wallet.wallet import Wallet
@@ -475,7 +476,9 @@ def __init__(self, acctMgr, acct, assetScreen):
         self.canGoHome = False
         self.ticketStats = None
         self.balance = None
-        self.settingsScreen = AccountSettingsScreen(self.saveName)
+        self.settingsScreen = AccountSettingsScreen(
+            self.account.relayFee, self.saveName, self.saveRelayFee
+        )
         self.stakeScreen = StakingScreen(acct)
         self.wgt.setFixedSize(
             TinyDialog.maxWidth * 0.9,
@@ -716,6 +719,16 @@ def saveName(self, newName):
         self.assetScreen.doButtons()
         app.home()
 
+    def saveRelayFee(self, relayFee):
+        """
+        Changes and saves the relayFee of the account.
+
+        Args:
+            int: The new relayFee.
+        """
+        self.account.relayFee = relayFee
+        self.acctMgr.saveAccount(self.account.idx)
+
     def stackAndSync(self):
         """
         Start syncing the account.
@@ -1832,7 +1845,7 @@ class AccountSettingsScreen(Screen):
     Account settings screen.
     """
 
-    def __init__(self, saveName):
+    def __init__(self, relayFee, saveName, saveRelayFee):
         """
         Args:
             saveName (function): A callback function to be called after the user
@@ -1846,6 +1859,7 @@ def __init__(self, saveName):
             TinyDialog.maxHeight * 0.9 - TinyDialog.topMenuHeight,
         )
         self.saveName = saveName
+        self.saveRelayFee = saveRelayFee
 
         gear = SVGWidget("gear", h=20)
         lbl = Q.makeLabel("Account Settings", 22)
@@ -1869,6 +1883,50 @@ def __init__(self, saveName):
         bttn.clicked.connect(self.nameChangeClicked)
         grid.addWidget(bttn, row, 1)
 
+        # RELAY FEE
+
+        # Set string constants.
+        self.lowStr = "low"
+        self.defaultStr = "default"
+        self.highStr = "high"
+
+        # Set values that are considered low, default, and high.
+        self.feeRates = {
+            self.lowStr: 4000,
+            self.defaultStr: int(DefaultRelayFeePerKb),
+            self.highStr: 114000,
+        }
+        self.feeLvl = ""
+
+        # Find the current level. Warn if the current level isn't one of the
+        # three.
+        for k, v in self.feeRates.items():
+            if v == relayFee:
+                self.feeLvl = k
+                break
+        else:
+            log.warn(f"non standard relay fee set: {relayFee}")
+
+        # Helper to check the current value.
+        def setChecked(btn):
+            if self.feeLvl == btn.text():
+                btn.setChecked(True)
+
+        row += 1
+        grid.addWidget(Q.makeLabel("Relay Fee", 14, Q.ALIGN_LEFT), row, 0)
+        row += 1
+        btn1 = QtWidgets.QRadioButton(self.lowStr)
+        setChecked(btn1)
+        btn1.toggled.connect(lambda: self.relayFeeChangeClicked(self.lowStr))
+        btn2 = QtWidgets.QRadioButton(self.defaultStr)
+        setChecked(btn2)
+        btn2.toggled.connect(lambda: self.relayFeeChangeClicked(self.defaultStr))
+        btn3 = QtWidgets.QRadioButton(self.highStr)
+        setChecked(btn3)
+        btn3.toggled.connect(lambda: self.relayFeeChangeClicked(self.highStr))
+        wgt, _ = Q.makeRow(btn1, btn2, btn3)
+        grid.addWidget(wgt, row, 0, 1, -1)
+
         self.layout.addStretch(1)
 
     def nameChangeClicked(self, e):
@@ -1882,6 +1940,19 @@ def nameChangeClicked(self, e):
         self.nameField.setText("")
         self.saveName(newName)
 
+    def relayFeeChangeClicked(self, feeLvl, e=None):
+        """
+        Qt slot connected to relay fee radio button clicked signal. Changes the
+        relay fee to feeLvl.
+        """
+        if self.feeLvl == feeLvl:
+            return
+        self.feeLvl = feeLvl
+        fee = self.feeRates[feeLvl]
+        self.saveRelayFee(fee)
+        log.info(f"relay fee changed to {fee} atoms/kb")
+        app.appWindow.showSuccess(f"using {feeLvl} fees")
+
 
 class NewAccountScreen(Screen):
     """